Rifled Cannon Liners (Sleeves) in 1.000" Bore size Coming Soon...........

[Cannon Cocker]

     Cannon Cocker,  we determined the parameters for stabilization by using various rifling twist calculators over the past eight years.  The best one we have found is:

                                                     A Calculator for Barrel Twist Rate by      http://kwk.us/twist.html       


   Although there are many different twist rate calculators our there in Cyberland, this is the one which has proven reliable for us.   

   You will find that the average of the twist rates for lead, steel and zinc projectiles may hover around the 50 or 60 inches for one complete twist, what you must always remember is that in the world of small cannon twists, there is no such thing as over stabilization. So the twist which you select to make or buy must be a logical decision based on the stabilization requirements of all the projos you expect to shoot in your cannon.  Because over stabilization  only exists in the most highly refined, ultra long range target shooting, you must logically discount it's siren song which will lead you to the false god called "Optimum Stabilization".  Your twist rates will become less quick and will attempt to provide the optimum for one length, one material and one size projectile shot at one specific velocity.

     The foolishness of this will become apparent only after you begin to notice that certain projectiles at lower velocities or perhaps made of zinc are only marginally stable or stabilize only past 200 yards (this has happened to us early in our tube rifling experiments).

     So, one in 42" is a low, all inclusive figure and one which was very carefully selected to give excellent accuracy in the vast variety of loads, projectiles and materials the small cannon shooter is likely to use.

Tracy

Those are some good points.  I can see how by using a twist rate calculator you might "optimize" yourself into having a twist rate that is not quite enough to stabilize.  And I agree that with our hobby by staying a little on the faster side, we're certainly not going to rip projectiles apart.  You must also also think that higher yaw off the line of trajectory, and higher wind drift are a non issue until much much higher twist rates than what the optimizers would calculate.   

That's the same calculator that I have been using, and it seemed like a good one, but I haven't done the kind of testing you guys have done. 

[Victor3]

   
10 groove James System Rifling with a constant twist of one turn in 42".  In this size, 1.0000" this rifling should stabilize any bullet of lead, zinc or malleable steel which is 1.7 to 2.5" long at velocities of 900 to 1,200 f.p.s.

 From here it looks like it may even do okay with a PRB. 

[Cannon Cocker]

I think you have the right firing position there.  Please make me one with a short stock in a flintlock version set up like a blunderbuss.  I'll just bring a modified log splitter to the range with me to ram home the patched balls. 

[seacoastartillery]

     Ha,  you are absolutely correct, Cannon Cocker, nobody firing a slightly faster twist is going to see any pieces flying off their projectiles, even lead ones!!  Please keep these figures in mind, guys;  our 1/6 scale 100 Pdr. Parrott rifle has one turn in 36" twist, which is pretty fast for a small cannon and it shoots groups between 2 and 3 inches all day long at 100 yards.  It is very close to a 1.000" bore at 1.067" Dia.  170 shots downrange from this sweet little coffee table cannon also taught us that it was sensitive to projectile velocity.  Shot at a traditional 1,250 fps just like the big boy originals, it clusters its steel bolts in tight little groups.  As you lower velocity to 900 fps the groups open up until you have bolts going through the paper at 50 and 100 yards sideways, but the paper at 200 shows that they have  finally stabilized.  At the lower velocity, the group sizes at 200 are nothing to brag about, however, as you might guess.  But, going back up to 400 grs. BP, (1,250 fps) from 250 grs., (900 fps) brings you right back to the bullseye and, once again, proves it's tack driver status!

    As you fellows can probably tell, we love talking and writing about this stuff.  I really think it's all the experimenting that we do to get the best accuracy out of any cannon that keeps us continually fascinated with small scale artillery.

    Victor,  I freely admit to being indignant about that PRB acronym, or am I ignorant about it?  Anyway, one of those two.  The closest one I can find after looking at about 250 is this:  PRB stands for "pressure relief balloon".  I believe that it refers to, not a standard rubber balloon, but rather a strong but hard piece of plastic directly behind the propellant charge on a Carl Gustav  M/42 20mm Recoilless Anti Tank Rifle which momentarily forces pressure to build up before it shatters for a more complete burn of the propellant and greater projectile velocity.  Mike and I examined one closely a couple years ago in a Tulsa, OK gun shop where our gunsmith friend works. Youtube has a video and stills of one going off.  OH my, don't walk behind one!!!    What did you really mean by PRB?

     Cannon Cocker,  OK, short stock with rock lock, got it!  We will give you one of those pointy tipped butt plates so you get the POINT each time you fire it, that we are not too pleased about special orders.  Shotgun butt you say??  Just for sissies says us!!

Tracy & Mike

[Double D]

PRB= Parrot Rifle Barrel?

[Victor3]

 Sorry. Patched Round Ball. I thunk everyone with a BP ML, either FL or CL, knowed that.

[Double D]

Victor,

I thought that was PL instead of CL.  But my ML's are all EIC English make so that may be the difference. 

[Cannon Cocker]

   Shot at a traditional 1,250 fps just like the big boy originals, it clusters its steel bolts in tight little groups.  As you lower velocity to 900 fps the groups open up until you have bolts going through the paper at 50 and 100 yards sideways, but the paper at 200 shows that they have  finally stabilized.  At the lower velocity, the group sizes at 200 are nothing to brag about, however, as you might guess.  But, going back up to 400 grs. BP, (1,250 fps) from 250 grs., (900 fps) brings you right back to the bullseye and, once again, proves it's tack driver status!

    As you fellows can probably tell, we love talking and writing about this stuff.  I really think it's all the experimenting that we do to get the best accuracy out of any cannon that keeps us continually fascinated with small scale artillery.

   

Tracy & Mike

I love talking artillery ballistics too.  Ya know, I've heard it several times from you guys about the higher velocities being critical to accuracy.  And my experimentation has shown that recently too, but I fought the urge to increase charges for a long time based on research pertaining to accuracy loss when the projectile drops back through the sound barrier.  I likened our guns to be more similar to air guns where the most accurate shooters try to stay well below the sound barrier at around 600fps.  Now I'm not saying that I have tried to stay that low (600fps), but I previously thought that staying under 900 or so would be best.  Do you think that adequate spin is the main factor contributing to accuracy in your experimentation?  In other words, if there were adequate spin at lower velocities, do you think that staying below the speed of sound would give better accuracy than being up in the 1250 range, or is there something else at play that I'm not considering. 

[seacoastartillery]

     Cannon Cocker,    Yes, we do believe that higher velocities are critical to accuracy, but not for the reason that you might believe.  We will try to integrate a second significant question you asked into the answer, because they are definitely related.  That second important question is:  Do you think that adequate spin is the main factor contributing to accuracy in your experimentation?

     Mike and I believe, based on all the empirical evidence we have gathered over the past 7 years, that with complete engagement of the sabot into the rifling grooves, comes adequate spin to stabilize the projectile.  We learned through lots of trial and error that this will only occur when the shooter uses an adequate amount of powder to create enough pressure to press the skirt of the sabot made of any appropriate material (annealed brass, bronze, copper, wrought iron or 12L14 steel) firmly into the rifling grooves for complete engagement.  From 2004 to September of 2006 we had a variety of accuracy, mostly depending on the powder charge.  Heavy charges were far and away the winners and consistently produced acceptable to superlative accuracy.  We just didn’t know why.

      When we visited the Paulsen Brothers in December of 2006 to show them our 100 pounder Parrott rifle, we put the accuracy question to them.  The first question from them was,  “Do you oil or grease your projectiles?”   We answered, “no”.  They said,  “Good, don’t ever do that.”  We asked, “ why not”?  “Because it will cause the expanding sabot to slip or skid across the rifling lands, rather than dig in to grip them, as it should”,  they said.   Well we knew that could not be the cause for our on again, off again accuracy, so we took lots of information home with us that we could try out, like consistency in velocity and starting the projectile quickly enough to flair out the malleable skirt quickly and forcefully to get complete engagement for reliable spin for each shot in the group.  And shooting into finely divided soil without rocks or gravel and then studying the dug projectiles for complete or incomplete rifling engagement

     Cannon Cocker wrote: "or is there something else at play that I'm not considering?" Do a few experiments with the following thought in mind:  Full speed ahead, 900 fps. be damned!    Then, by all means let us know if accuracy improved.

     The speed of sound is approx. 1,100 fps, depending on the ambient temperature of the air through which the sound is traveling.

     We don’t have any measurable results which indicate an accuracy loss or gain depending on which side of 1,100 fps your bolt is traveling.  The same goes for the bolt breaking the sound barrier as it slows down during the descending branch of it's trajectory.

Thanks for your well thought out questions, I hope we have been helpful.
 
Mike and Tracy
 
   
 
 
 

[Double D]

Sound like  Dr.  Manns work on obturation, revisited...

[Cannon Cocker]

     We don’t have any measurable results which indicate an accuracy loss or gain depending on which side of 1,100 fps your bolt is traveling.  The same goes for the bolt breaking the sound barrier as it slows down during the descending branch of it's trajectory.


 
 

Thanks  for the detailed answer.  Thats interesting that you found no significant deterioration of accuracy pertaining to velocities over the sound barrier, particularly when the projo started out super and ended sub.  I've been kind of hung up on this for a while having read a ton of ballistics stuff relating to this, boat tails etc.  I have no less than 6 different projectiles I've shot at ranges from 100 yards to 600 yards, with various charges for my Confederate mountain rifle.  Some day I'll post pics and findings in detail, but in general, most of the experimentation has to do with getting good rifling engagement with only 3 saw tooth gain twist grooves with a rate of one turn in 10ft. 

[seacoastartillery]

     You guys who wanted a heat shrunk, cross pinned and welded breech plug win.  Mike and I were going over the probable uses and host cannons for these 1.0000" sleeves and we discovered one problem with the screw breech.  It's just too BIG!  That's right, we were so fixated on the rifling and how to make it perfect, that we neglected some of the integration calculations.        This first sleeve was rifled with James System rifling to be authentic with respect to the first arsenal manufacture of conversion rifles of ten grooves from new made Bronze 6 Pdr. Field Guns M1841 in the 1850s.  This tube has similar wall thickness to the chase of the 1861 Parrott and Ordnance Rifle. 

     The original Bronze 6 Pdr. has a OD of 6.5" just behind the astragal and fillets on the chase eight inches behind the muzzle face.  Now since the 1.0000" bore dia. sleeve is intended to be inserted into a 1/3 stand-off scale gun, that same thickness would only be 2.167" dia. Because we would use a 1.25 X 12 threaded breech plug to allow room for a gas sealing surface to keep BP residue out of the threads, we would weaken a 1/4" wall tube too much to be viable, so a 3/8" wall thickness would be necessary.  Adding a .375" thick wall to the 1.0000" I.D. rifled sleeve would give you a 1.750" O.D.  If you subtract this figure from the 1/3 scale bronze 6 Pdr. smallest OD, you get .417".  Divided by two, that's only .2085" all around thickness of the cannon which you must then bore out with about .050" total clearance for no hassle sleeve insertion, making the walls even thinner at .1835"
 
      Less than 3/16" of the original 1/3 scale wall thickness is left!  Too little, when you consider that the vast majority of installers will be drilling the deep cannon bore hole with a twist drill, NOT a gundrill.  The chance of a wandering drill breaking through the thin wall is just too great!
 
      With the heat shrunk breech plug to seal the end from hot gasses, cross pinned for insurance and welded for strength, you can effectively use a 1/4" wall thickness sleeve for this size bore.  The total O.D. is only 1.50", making the cannon metal a respectable .3085" thick all around after subtracting the clearance figure of .050".  Any machinist can drill the clearance hole required with his much material all around this thinnest point.  The cannon tube O.D. of the breech end is 9.8" just in front of the breech band over the powder charge in the sleeve.  1/3 scale O.D. is 3.267" making the wall thickness of the cannon tube alone, .8585" with .050 installation clearance.  Added to the rifled sleeve wall thickness of .250", this makes the total wall thickness over the powder charge to be 1.0855" which exceeds the wall thickness recommended  by the 1:1:1 Rule.   
 
      So, after we do some heat shrink experiments on the same material we will use for making the sleeves, we will cross-pin and get one welded up by an expert welder that we use for all of our welded fixtures and parts.  This guy also makes incredibly beautiful Damascus steel knives.  His work is very precise and detail oriented.  After that we will bolt the sleeve to our landscaping timber shooting fixture and go to the range for accuracy testing.  After we get the accuracy we want, we will make one out of 1/4 inch wall thk. material and do strength testing followed by more accuracy testing.  The third prototype will be inserted into a 1/3 replica bronze 1841 tube and tested for accuracy once again.  Only if all tests are passed, will production sleeves be made.
 
     That's the latest; we will quickly answer any questions that you may have.

 
 Mike and Tracy
 
 PS     Cannon Cocker, we would love to see a post on your experiments with the Confederate Mountain Rifle.  That would be cool.
 

[Double D]

Any thoughts on the 3/8" minimum liner wall thickness required by AAA and N-SSA?

I really  think that only applies in cases of gun made of other than steel. I would think the total of a steel liner and steel barrel greater than 3/8" would be well with-in the guidelines.

Bronze gun, now that's different.

Also how thick will this Breech plug be?  We need a 1" thickness minmum.  Again referencing the  N-SSA guidelines this can be a combination of liner and existing cannon wall.  The Breech plug does not have to be 1". If it is 1" and welded and pinned then it can't be trimmed to fit a specific gun.  Using as is if  1" would put the breech and vent a bit more forward than desired.

I have to much free time...

[Cannon Cocker]

Any thoughts on the 3/8" minimum liner wall thickness required by AAA and N-SSA?

  Again referencing the  N-SSA guidelines

Not so sure why we care about N-SSA guidelines (pertaining to Seacoast's liners).  They (N-SSA) will never be inspecting or care to inspect anything but a full scale gun because less than full scale replicas are no longer allowed in their events.  And if we are using them as a guide to ensure structural integrity, I would rather rely on Seacoast's engineering abilities than the somewhat inconsistent collage of rules put forward by the N-SSA. 

[Double D]

Because N-SSA is citeable source as a creditable recognized and accessible set of uniform safety standards established by a Nationally recognized Organization.

N-SSa is not a necessarily a source of greater knowledge or wisdom.  The may be and they may not be.  While you may be at odds with their philosophy, I have only seen two credible criticism of the engineering in the rules.  Victor constantly points out the lack of definition as to the minimum type seamless to use and others question the definition sweat fit.    Both of these I believe point to the lack of updating to modern terms and definition.  Poorly worded yes, we all agree.  Over engineered, haven't seen that questioned and fail to find fault in that.

While I have no concern myself about Seacoast's bona fides, they do not have national reputation that N-SSA  has and they would be subject to severe scrutiny if summoned to court.   

Your Attorney will find it much easier to defend you in court when he can present to a jury that you used due care in building your gun since you built using material that was built to the national recognized standards established by a Nationally recognized organization.   

So let mevsummarize all this when you build a gun CYA

[KABAR2]

years ago I had a project that required a shrink fit.... but I went about from a different angle the plug was knurled and then put in place as far as I know it has not moved in 20 years.... this plug was not welded either...... but it was not an aplication used with BP.... might be an interesting experiment.....  just a thought......

[seacoastartillery]

      Seacoast Artillery Company’s most important goal has been and will always be customer delight.  We do lots and lots of special things to make sure we achieve that goal.  Frankly, being problem solvers for our entire careers in quality assurance and small manufacturing , puts us in right frame of mind to please all reasonable customers. We don’t have any reluctance to answer  the build-related concerns raised by the global moderator.

     First, let’s address the 3/8” minimum sleeve thickness guidelines published by several of the cannon shooting clubs or associations.  Even though our 1.0000” bore dia. or 1.7500” bore dia. scale cannon sleeves will never be used in the cannon competitions held under the auspices of the AAA or the N-SSA based on their full size only rules,  we still feel it is important to give our customers who want thicker walls the option to have them if they wish.

     Therefore we will supply the first ten sleeves we make with walls .625” thick at NO EXTRA CHARGE.  The customer or their machinist can turn the wall thickness down to a reduced size to fit a particular cannon.  We specifically warn against any wall thickness less than Ľ”. 
     
     Now, as to the positioning of the vent, we will respond to a specific customer request for a reduced length of breech plug so as to meet the cannon club’s rule for one caliber metal in the breech area.  This request must be in writing and signed by the customer in ink. Our safe minimum for the length of the welded breech plug, which we will maintain for the liner alone, is ˝ caliber.  Deeper drilling of the cannon’s bore may be necessary to position the vent so it is 1.5 to 2.0 calibers forward of the rear edge of the breech ring, although we do not recommend this.  We dislike slanted vents and believe they are dangerous to the person or persons firing the cannon.

      As far as the legal-eagle stuff goes, we have enough experience to know how to save prototypes, document all the testing of them, keep records of materials ordered with noted tensile values, etc.  We are very familiar with courts and courtrooms, both State and Federal. 

     That’s about enough of that!  Any different type of questions will be answered.  We are done on the subject of regulations.   Accuracy?  Now that’s a subject of a lot more interest to this group, I bet. 

Mike & Tracy
 

[Cannon Cocker]

       Accuracy?  Now that’s a subject of a lot more interest to this group, I bet. 

Mike & Tracy

Alrighty then.  I have seen and followed the threads showing the accuracy of the barrels you have made and tested, but I don't think I have ever heard you state which combination of rifling and bolt was the MOST accurate in all the testing you have done.  So what is the golden combination that made you look at each other, smile with wide eyes, and silently mouth "holy &^*#"?

[seacoastartillery]

      Referring to which “combination of rifling and bolt was the MOST accurate in all the testing you have done”, Cannon Cocker wrote:  “So what is the golden combination that made you look at each other, smile with wide eyes, and silently mouth "holy &^*#"?

     That actually has happened to us just twice in the eight and a half years we have been using our rifling machine.  The first time in 2005 was after a year of on and off building of our Sine Bar Rifling Machine and development of the Rifling Head, it’s most important component.  We selected  1.0000” I.D. / 3.00” O.D. mechanical tubing (DOM) for it’s excellent size consistency from end to end and roundness of the I.D. for our first cannon tube.  After ruining the first three attempts at rifling due to flaws in the Rifling Head, we did a whole bunch of hook cutter experiments by holding the cutter in a special Bridgeport Mill fixture with an R8 projection.  We held milled sections of the 1026 steel tube in the Kurt vise and ran it by, (under power)with the tool held rigid in the quill.  We had Positive Rake angles all the way from 8 degs. down to 1/2 deg. and Negative Rakes from ˝ deg. to 5 degs.  3.5 degrees, positive, seemed to cut the smoothest on the 1026 steel.  By contrast, we found that a full  5 degrees positive rake angle worked the best when cutting 4150 Rc 30 ordnance steel.

     Finally we took our fourth experimental cannon tube to the range along with solid 12L14 bolts, 1.75” long, 1.0000” Dia. and weighing 6 oz.  They had a .020” thk. skirt and a truncated cone ogive.  The rifling was 4 groove and only .187” wide and .012” deep with lands a whopping .5984” wide!  Believe it or not the 4 grooves were indexed by eye as we had not made our first indexing collar yet.  We were so happy to have finally made grooves that seemed to have consistent spirals going down the bore and were not all messed up with chatter marks from machining that we zoomed out to the range (180 miles round trip) with only 10 very carefully made bolts to try on paper and 2 to shoot into a soft dirt bank.  We shot the rifling engagement rounds first and when we dug them out, we found that they showed the bolt’s skirt had engaged with every groove.

     The 100 yard target looked awfully small and lonely way out there on the very green prairie in June of 2005.  We fired  5 shots, carefully cleaning the bore after each one, and then started the long walk to the target.  When we finally reached it, we could hardly believe our eyes. I can’t remember what we said, but we did look at each other with amazement and delight.  The shot gun type patterns of past sessions had been replaced with a nice, tight 3.25” group and all five had printed holes with nice crisp edges (no more YAW!).  The pictures here are from our website, but are necessary to illustrate the story without having disjointed look-ups.   






 
     Yes, of course we saved the best for last, any story teller worth a darn would tell you the tale just this way.  After the euphoria of success, the Seacoast boys were brought back to earth precipitously when they tried to rifle 4142 Colt Crucible Steel and later 4150 Colt Crucible Ordnance Steel with the same hook cutter and the same rifling head which worked so well with 1026 steel.  As we worked on our first seacoast gun, the 100 Pdr. Parrott Seacoast and Navy 6.4” rifle, we also visited commercial rifle makers who made their own barrels from 4140 and 4150 barrel steel.  Gathering tips and specific information here and there, we decided to completely rebuild our rifling head and the all important hook cutter.  Six months later we had one that worked with the extremely tough and pre-hardened 4142 steel we bought.  Long hours of rifling and re-rifling cannon tubes followed.  We had at one time eight,  $400  tubes in the scrap bin to be drilled and reamed to larger sizes when we made them someday in the distant future.

     Instead of a hinged cutter, we now had a floating cutter elevated by an adjustable wedge and held in place by spring pressure from a large coil at the front.  With a full 5 degs. of Rake Angle, we were finally ready to rifle cannon tubes just like other cut-rifled modern rifle barrel makers do, but slower due to a manual Rifling Machine.  Due to extremely focused attention during the alignment phase of construction, we built a machine as good or a little better than the best Pratt and Whitney sine bar rifling machine out there.  We even started to use Swedish Tool Steel , FAGERSTA WKE 45.  It remains sharp for more than 1,000 strokes of our rifling machine, enough to do all 7 grooves to .023” deep on our Brooke tube.

     Although we came to expect groups in the 2.5” to 3.5” range from the 1/6 scale 100 Pdr. Parrott Seacoast rifle, we saw even greater potential from the 1/6 scale 7” Treble-Banded Brooke rifle.  Using an authentically shaped bolt made from 12L14, malleable steel with very close tolerances on critical features, we began to expect sub 3.00” groups for 5 shots at 100 yards. Most hovered in the 2.00” to 2.75”  range.  Although the development targets and the final test targets are owned by the owners of these cannons, we did save a target backer from the most outstanding group we have shot to date. See photo below:



 
     The following specs are examples of the close tolerances held on the lathe turned ammunition that we make and use.  All bolts shall be .003” +/- .0001” less than bore size.  That’s right, we only allow.0015” all around windage!  Yet those 2.00” long steel slugs slide all the way down a clean bore.  Bore straightness is held to .003” per foot, less than .005” over all.  Bore size is held to 1.1670” +/- .0002” and the muzzle end can never be larger than the breech end of the rifled section.

     The third prototype tube provided startling results one windy day in 2007.  Shooting from the top of a knoll 75 yards south of our normal testing position, we could see the end of the almost dead flat valley bottom stretched out ahead of our heavy duty shooting bench to 1,200 yards.  The target at 100 yards was actually about 10 feet lower than our cannon muzzle, not enough difference to cause any problems.  The wind, however,  was from 12 o’clock and between 15 and 20 mph.  Fortunately the direction did not change in the 45 minutes it took us to fire the five shots.  As we walked down to check the target we had low expectations as we could see only one hole without a spotting scope.  Our only spotting scope gave up only 3 months before we shot this group!  As we got closer we could see two holes, but where the heck were the others??  Finally at about 40 feet we could see the one hole was a cluster of four shots and the other hole was clearly a flier.  See the target stats below:


Target Statistics:

Date……………………………………………………………………………..July 7, 2007
Time……………………………………………………………………9:00 to  9:45 A.M.
Size of 4 –shot cluster measured center to center..........………..1.10”
Size of group with flier measured center to center………………….3.85”
Powder charge wt……………………………………………………….….518 grains
Projectile wt……………………………………………………………………….9.02 oz.
Temp (F)………………………………………………….…………….….70 to 75 degs.
Wind…………………………………………………15 to 20 mph from 12 o’clock

The actual target was retained by the customer.
 
     The photos below help tell how this target was made possible.


This pic shows Brooke triangular or modified hook-slant rifling being cut.  This tube is 70% complete.




 
The dirt bank from which fired projectiles are recovered.




 
Firing into the soft dirt.



 

These bolts were recovered after being shot into soft dirt.  On the left a Brooke bolt and on the right a 100 Pdr. Parrott, chill nose bolt.  Both engaged the rifling very well.




 
One of the many group development targets, this one shows vertical  stringing due to lack of preponderance in the 2^nd prototype.  The trunnions were moved .280” forward to place more weight over the elevation screw.  The 3rd prototype range testing showed none of this stringing.




 
Seacoast Artillery’s modification of a Pacific Tool Push reamer.  Six brass tubes deliver compressed air and water soluable cutting fluid to the reamer’s leading edge.  Swarf is blown out at the tube’s muzzle.




 
The 4150 steel  blank round is held in precise alignment with the gundrill by a high precision roller bearing and a robust, shop-made support clamped to the lathe’s ways.



 

These One Inchers are NOT TOYS!!  Think before you act.  Do Not Let ANYONE Hurry You!  Be careful.  Be Safe.  Have fun.  The rain came down so the   7” Treble-Banded Brooke Seacoast and Navy Rifle  was fired from inside the barn owned by one of Spuddy’s friends near  Presque  Isle, Maine  last fall.







     That's it for tonight guys.  We have answers; ask your questions!

Mike and Tracy

 

[seacoastartillery]

     Today, after a nice visit with my grandson, Mike and I went to work on the rifled sleeve breech plug.  First we had to find a small boring bar to clean out the rifling for three inches, 1" for the plug recess and 2" for the chamber area so it can be sponged effectively. The story of today's work on the Rifled Sleeve is in pictures below.

Tracy and Mike


Setting the boring bar for .012" deep rifling removal.




The rifling has been removed for 3" and the breech plug recess was cut .025" deep all around with a length of 1".




The breech plug was turned to a size which is .002" larger than its recess in the sleeve end.  Also it has a full hemispherical radius in its front end.




The chamber end of the breech plug or the end of the chamber after insertion with the perpendicular gas sealing surface which mates with the .025" wide sealing ring at the bottom of the breech plug recess in the sleeve end.




Mike applies two propane torches to heat up the breech plug recess to between 500 and 600 degrees.  With a .002" interference fit at room temp, we need at least 500 deg. F. to get a .003" expansion ( steel expands at .000006" per deg. F.  per inch) of the recess so the breech plug fits and can be tapped lightly for one half inch to effect alignment and then wacked with the sledge hammer for complete engagement of the gas sealing surfaces.  Moments later the shrinkage of the recess is complete further tightening the breech plug, providing more gas blockage.




Hot!  Don't touch.   You can see the bevels on both parts requested by our welder to provide the conditions for deeper weld penetration.

[Cannon Cocker]

With it being epoxied into another barrel, the shrink fit is probably overkill with a good weld, but over engineering is better than the reverse.  We can count on you guys to make everything as good as it can be made.  Now if you pin it too, well that's just for fun. 

[Victor3]

With it being epoxied into another barrel, the shrink fit is probably overkill with a good weld, but over engineering is better than the reverse.  We can count on you guys to make everything as good as it can be made.

 Maybe so, but the shrink will make sure that no gas can get between the bore and plug.


 As far as the strength of a shrink fit goes, my Wife's Grandfather worked as an assembler for Sikorsky decades ago. I don't remember the model of helicopter but he told me they attached the drive shaft to the main rotor assy with nothing but a shrink fit. 

Now if you pin it too, well that's just for fun.

More like a waste of time, IMO.

[Cannon Cocker]

 Maybe so, but the shrink will make sure that no gas can get between the bore and plug.


 

Since it's concave on the face of the plug (back of the breech), isn't it going to obturate with every shot?

[seacoastartillery]

    Well we finally are getting to the 1.000" rifled sleeves that we told you we were thinking about offering a year and a half ago.  We may be slow, but we are good.  When contemplating the purchase of a rifled sleeve, what is more beneficial, quality and accuracy or speed of delivery?

     Here's the word on "Sleeves" VS "liners".  Among knowledgeable artillery providers and makers, the word liner is used to identify the end capped piece of steel tube which has been cast in place into a cast iron cannon tube.  Used with artillery in mind, the word "Sleeve" means a rifled or smooth bored mechanical tube with a breech plug installed which is inserted into a cannon bore which has been enlarged to allow the sleeve to fit while completely coated with a high strength epoxy mixture. 

     Right now we are working on rifling the second of three into which we have installed the breech plugs.  Double D.'s rifled liner is now complete, He  was our first customer for this product and as of a couple days ago, the plan is to visit us on the way back to Cut Bank, Montana in late March.  So while we give him some jazz occasionally, we sure do love him as a loyal customer!  And his Montana Cannon Shoots are the very best that can be devised too.  Cannon Cocker's is next and after that anyone who wants one is welcome to buy.

     The price is $399 and for that you get a rifled tube which has been as carefully rifled as our $17,500 premium cannons.  How can we offer these so inexpensively?  The premium cannon tubes are pre-hardened 4150 ordnance steel, from 215 to 265 pounds worth.  Our cost is 500 to 600 dollars EACH!  Extensive machining adds a lot of cost too as does an absolutely authentic upper carriage, chassis and platform, all from white oak.  These weigh 175 pounds when complete.  the sleeves are as carefully machined, rifled ,assembled and professionally welded after heat shrinking the breech plug in place.  The bore I.D. is 1.000" , the O.D. is 2.00" making the wall thickness .50",  These are 30" long. so for most one third scale cannons, you have 2"  to 5" to trim off to your final dimensions.  It takes 2 to 3 days to rifle each of these tubes.  Why so long?  The rifling depth is .014" deep on each of the ten grooves.  Removing .000150" (one tenth fifty millionths)  per stroke, 93 strokes per groove, or 930 strokes total are required to get the tube completely rifled.  Neither one of us can do more than 400 strokes in a six hour day and stay focused.  It takes about 4 days to complete a 1.000" diameter sleeve carefully and correctly.

     The following photos are a visual update on this product.  One has been seen before, all the others have not. 


Tracy and Mike


Bored 1.00" deep this recess for the breech plug is .002" undersize and has a .040" 90 deg. shoulder at the bottom to stop the breech plug solidlym as the effects of heat shrinking tighten the plug firmly into it's proper position.




The next two are ready for rifling.  The breech plugs have been heat shrunk into place, see the color of the steel?  They are ready to be rifled now; yes, that's right, we blind hole rifle them just like the craftsmen did in Parrott's, West Point Foundry in Cold Spring, New York on the Hudson River back in 1862.




This is the top of the new rifling head with the reduced size slot for less cutter width.  The screw at the far left adjusts the distance from the rear of the radius cornered chamber to the start of the first cut of each groove.  The one close to the rifling head body is the adjuster for the "Waterfall Cut" which starts at the forward end of the chamber and advances the cutter head .005" per stroke and ends when full groove depth has been achieved.




The Rifling Head in its "Home" position where it is cleaned, oiled and .005" advance adjusted for each stroke.




I finally got a shot of the hook cutter cranked all the way up so you can see it and it's critical angles which are 5 deg. rake and 13 deg. relief.




I got this almost straight on shot by putting my elbow in some nasty goo/ old grease, new oil and very fine metal particles in oil called "swarf"  from the finishing cuts.




Another view; the rifling is finished, but the tube has not been cleaned yet. 




Remember this one?  It shows what the rifling helix looks like.  It is 1 turn in 42".




So, whether you are building an exhibition cannon such as this one, or a one third James rifled m1836 6 Pdr. field gun, your rifled sleeve from Seacoast Artillery will fit right in.




Maybe a one-fifth scale 24 Pdr. Seacoast Gun is in your plans?

[MKlein]

Wow what a steal! You guys are going to be eating crackers and bologna for a while.
 
I bet it would look good in this gun
 

 
Or this one
 

 
http://markerhunter.wordpress.com/2009/09/07/james-rifles-part-4/

[seacoastartillery]

  Quote from Cannon Cocker:   "Since it's concave on the face of the plug (back of the breech), isn't it going to obturate with every shot?"  No, because the 1/4" radius leaves a fairly thick tangental edge where it flairs out on the chamber's side.  The heat shrunk breech plug is the item that stops the flow of hot black powder conflagration gasses from the rear of the chamber, and the expert welding solidly joining the end of the tube and breech plug.


     MKlein writes:   "I bet it would look good in this gun", speaking of the huge early war James System Rrifling and Banding job done on a 42 Pdr. (7") Gun that we found in western Pennsylvania in 2009 in the small town of Titusville.  Does that name ring a bell?  It was one of the first oil patch towns this country ever knew.  We saw one of these mounted vertically on a wall of the Tredegar Foundry in Richmond, Virginia and I stood next to it and I seem to recall that the top of my head was only at the half way point.  These cannon are long!  His other choice is an experimental type III James rifle made of cast steel with an applied trunnion ring.  I think Mike, Dewayne (De_Lok) and I spotted one of these at Shilo Battlefield when we visited about a year ago.  Below are my pics for "dream guns" that may or may not ever get built with a rifled sleeve inserted.


Tracy & Mike


This pic is attributed to the Steen Cannons site and shows what magnificent work they do with bronze guns.  My love affair with the Bronze 6Pdr. M1841 Field Gun began long, long ago and I still think it's simple, classic lines make it the most beautiful cannon every made.  Someday I will bite the bullet and buy a big chunk of bronze to turn down into a half or third scale 1841  6Pdr.  with a rifled sleeve of our manufacture complete with James System Rifling.




Another view featuring the tulip muzzle of that fine gun.




Something a little different, we would love to make a rifled  Iron 6Pdr. M1819, the "Walking Stick".  I think the very slender lines of this model make it ideal for a half scale model with the ONE INCH Rifled Sleeve.   This one has a "Trumpet" muzzle flair.




Another "Walking Stick" gun.  This one is being fired in winter conditions with snow at the edge of the lake, a cool photo from a reenacting group in Maryland.




Another candidate for a rifled sleeve, one of our favorites having lines very similar to the bronze M1841 is this Iron 6Pdr. M1836 that we found in Lancaster, New Hampshire in 2007.  The tube was in nearly perfect condition then and we hope it still is, a wonderfully cared for and beautifully shaped gun.  A one third scale gun with a one inch liner would be really nice to own.




That tulip shaped muzzle swell again, absolutely gorgeous.  A model 1836 cast in 1837, this is only one of three still existing.

       

[Cannon Cocker]

   

I'm getting excited about owning an, accurate, superbly rifled sleeve from you guys.  It's going to be hard to decide what gun to make with it.  All the possibilities are so cool. 

Can I please have the one with the deep purple plug.  That one has a 1/4" MOA mojo goin on.  I can tell.

[seacoastartillery]

     Quote from Cannon Cocker:

"I'm getting excited about owning an, accurate, superbly rifled sleeve from you guys.  It's going to be hard to decide what gun to make with it.  All the possibilities are so cool. 

Can I please have the one with the deep purple plug. That one has a 1/4" MOA mojo goin on.  I can tell." 



     HA!   Anyone who can get a superb Whitworth rifled cannon to come together as you have must know something that I don't.  So I am going to take you at your word on the imagined excellent accuracy of the one with the deep purple plug and keep it for myself.    Whoa Nelly......I bet that chaps your jeans!...................................Only kidding! You can have it.  As far as schedule is concerned, Mike says we should keep on building these until the seven 1.000" sleeves are all rifled and welded.  The third will be done on Sat. so there are 4 more after that plus welding 2 days for delivery and processing time.  End of the month, I would say plus a week to find heavy tubes, get them and package the sleeves,etc.  The S&H is $35 for each sleeve ordered and $399 for the 30"long, 10 groove, rifled sleeve.  The O.D. is 2.00" dia. and the wall thk. is .500".  If you have any questions about this fine product from Seacoast Artillery, please email us at   seacoastartillery@gmail.com    Thank you.

    If you are waiting for the 1.75 inch bore model to become available, please tell us why.  Neither Mike nor I can figure out why such an odd size ended up being the most popular.  Bye the way, we already bought the steel tubes for this size, so we are serious about producing them, but we just Cannot understand the popularity of that size.  Is it because of the fact that it is close to normal smoothbore, Golf Ball size of 1.72" diameter??

Someone please tell us.  Thank you.

Tracy & Mike

[Cannon Cocker]

  is it because of the fact that it is close to normal smoothbore, Golf Ball size of 1.72" diameter??

I hope not. 

Firing a golf ball out of that perfectly engineered barrel would be like using the 150mm electromagnetic rail gun for those tests where they fire a saboted chicken at aircraft windscreens! 

[Double D]

Tracy,

A suggested source for heavy card board tube would be a carpet store.   They throw those carpet rolls away.