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

[Double D]

 

 
A 7" Brooke rifled tube at the Washington Navy Yard with triangular rifling taken off the raider CSS Florida.
 
 

From Vicksburg, Mississippi we have the famous "Widow Blakely" muzzle showing it's unique, Blakely Hook-Slant rifling.

Ratchet Rifling.  This is from the memorandum on development of the .402 Enfield Martini and used in Model experimental rifle  1882.

Brooke Rifling, bore of a 6.4-inch Brooke. Brooke rifling is often erroneously called "hook slant" rifling. Instead it is a set of lands with triangular grooves set into the bore. This style of rifling is also one of the traits distinguishing the Confederate gun from the Federal Parrott rifles. Brooke's design may have borrowed some ideas from the Parrotts, but had as many differences as similarities
http://www.civilwaralbum.com/misc/washington_dc12.htm

I think it matters where you are in the world as what it was called. 

[Victor3]

 I don't see how the Lancaster Oval Bore could work well in a muzzleloader. 
 
 Without a minimum of three points of contact, the projectile would have opportunity to sit cockeyed (off C/L to the bore) upon loading, no?

[Double D]

I don't see how the Lancaster Oval Bore could work well in a muzzleloader. 
 
 Without a minimum of three points of contact, the projectile would have opportunity to sit cockeyed (off C/L to the bore) upon loading, no?

Victor,

As I remember from the many discussion on oval bore over on the  British Militaria board the projectile is round and minor diameter of the bore.  The projectile obturates on firing and fills the oval.  Also as I remember, nobody shoots it well, which I have always suspected is for the reason you give.

[seacoastartillery]

      With my ego severely battered and bruised after all the errors in the "Flush it down the toilet site" I decided to use recently without thoroughly checking it for accuracy, I tried to find one which will be easy on me, you know, no challenges to it's accuracy.  Off course I forgot about our friends in the U.K and Australia which you shouldn't do if you are talking about  Armstrong-Whitworth  cannon.  Mike and I found this one at the midpoint in one of our 6,500 mile trips around the United States in central Vermont at Norwich University on the Upper Parade.

Tracy


Has anybody seen rifling like this on any other field artillery?  What would you call this unique staright, then twist pattern?  What possible purpose do you suppose this layout served?  We believe that twist segment is a straight twist and NOT a gain twist, but we can't be sure about that.  Next time we are going through Vermont, we will check that out. Click to ENLARGE the image.




The unusual rifling belongs to this Armstrong Whitworth RF (Rapid Fire?) field piece.   Pic prev. posted, but needed for those who want to do a little research.




This is what this field piece looks like, minus the breech block which was kept in the arms room when I was a cadet there.  It had been converted to shoot 10 gauge blanks and was used as a salute gun.  Pic prev. posted, but needed for context.  I like the long, slender tube and cool looking carriage.

[Victor3]

I don't see how the Lancaster Oval Bore could work well in a muzzleloader. 
 
 Without a minimum of three points of contact, the projectile would have opportunity to sit cockeyed (off C/L to the bore) upon loading, no?

Victor,

As I remember from the many discussion on oval bore over on the  British Militaria board the projectile is round and minor diameter of the bore.  The projectile obturates on firing and fills the oval.  Also as I remember, nobody shoots it well, which I have always suspected is for the reason you give.

 Interesting DD,
 
 Come to think of it, even in a breech-loading cartrige rifle using a groove-diameter bullet in an oval bore, two small areas of bore diameter in the rifling would still allow it to start crooked into the throat.
 
 Two-groove Enfield rifling would seem to be both easier to manufacture and allow the bullet to start straight upon firing, increasing accuracy.

[Victor3]

What possible purpose do you suppose this layout served?

 Just a WAG, but maybe the designer assumed that higher velocity with a given charge could be acheived by using this form of rifling over a constant twist.

[gunsonwheels]

Kinda reminds me of highway and railroad design though.  When they both started they went from a curved section of road/track directly to a straight section of road/track.  When trains started to regularly jump the tracks at the point of transition someone figured out it required infinite acceleration of the engine/vehicle right at the point of transition for it to track the rails/road.  So enter the spiral... all railroad trackage has a spiral (a curve with a changing radius starting at "0" and progressing to the same radius as the curve it is about to enter) entering and exiting a curve (exiting spirals changes from the curve radius back to zero (straight)).  All of our freeway curves also spiral into and out of their curves.  We don't notice it but without it, is akin to yanking the steering wheel from straight to the curve's turning radius and yanking it again from the curve's turning radius back to straight.
 
So if the rifling goes from straight to a constant rate of twist it would likely tear out the rifling or do some nice metal shearing of the projo/sabot.
 
So is it a constant twist or a spiraling twist??
 
GOW

[seacoastartillery]

     Victor,    Your theory sounds as logical as any we have heard.  Never have found a word about the reason for this rifling layout in print.
 
       GOW,    Very interesting info on the RR and Highway transitions.  Makes sense to us.  We did not have anything to measure the gain or lack of gain twist when we were there last time.  Next time, probably this summer or next we will measure it and report the result.
 
 
      Now we will depart from the modern, and take a walk down history's lane to bring you a most unusual rifled cannon find.  Fort Ticonderoga, in upstate New York is one of the most fascinating places in the entire United States for the artillery enthusiast.  The incredible beauty of the surrounding countryside doesn't diminish it's allure either.  While there are just a few original French and Indian War and Revolutionary War pieces on display, those few are very unusual and rare in this country, an example of which is the huge, 12" French Seacoast/Siege Mortar on display. 
 
      What they do have in large numbers are French and Spanish Bronze cannon.  Most of these are guns in the 12 to 24 pdr. range along with a display of 8 or 9 bronze mortars from 6" to 15" bore size.  We know very little about these bronze guns.  Cannonmn, John Morris is our resident expert on these guns and perhaps he might have some information on the rifled French (we think) gun we found in the right front water battery.  Please see photos below:
 
 Mike and Tracy
 
 
 Looking south toward Lake Champlain.  Vermont to the left, New York to the right.
 
 
 
 
 A holder for a rear sight can be seen here.
 
 
 
 
 This gun has very little decoration, but you can see a mounting place for an off-set front sight, plain dolphins and 3902, 3202, or 3209  on the right trunnion face.  The weight, perhaps?
 
 
 
 
 And here is the kicker, a Rifled Bore.  The questions, of course, are rifled by whom?  When?  Where?  Frankly, we don't know.  We heard at the fort that most of the bronze cannon came from South America.  That's all they knew about them.  This photo also shows you why it is foolish to stick your hand into a cannon's muzzle without looking first!!  Yes those are live paper wasps on that nest.
 
 Cannonmn, can you help us a little on this topic?

 
   

[cannonmn]

It looks more like a Spanish gun than anything, to me.  The breechface has a uniquely "Spanish Bronze Cannon" shape they've used a lot, for guns from 1-pounder on up.
 
The rifling is 6-groove Beulieu type.  Spain began using this system in 1862, to convert old muzzle-loading smoothbore guns to more modern rifles.  The shells had two rings of copper or zinc studs sticking out from the cast iron body to engage the rifling.  Look up Beulieu system on Google.  He was the workerbee, and often his boss' name, begins with T, is attached to the system instead.  I've shot guns with that system.  Projectile moulds tend to be a bit complex, sometimes many pieces of it need to be assembled for each pour.
 
If you want to see a whole bunch of old smoothbores with this rifling, look at the website for Leutze Park at the Washington Navy Yard.  The photos are still there although the bronze may have totally dissolved by now, have not been there in a while, makes me sick every time I see the dark green stains on the concrete mounts, and find yet another piece with all the markings, or most of them, eaten away by the acid rain.  Makes me want to find some to slug, really, but I tend to fight with my keyboard and video camera, not my fists anymore.   
 
Last time I visited there, a friend noticed that some of the Spaniish guns that had been rifled had four lighter-colored (kind of gray as opposed to the greenish gun) round spots over the trunnions.  He then determined that this was where the dolphins had been, and they'd been removed almost certainly at the time the guns were rifled, to leave room for the line of sight for the newly-installed sights.  The Ft. T. gun may have had dolphins also, only close examination would tell.
 
For anyone who doesn't know, the "cannonmn" channel on you-tube has probably 8 videos which point out in ugly detail the disintegration of the bronze cannons at the Wash. Navy Yard.

[seacoastartillery]

    Thank you Cannonmn.  John we sure appreciate your help in identifying this cannon and letting us know what system of rifling is present here and dating this system's early use.  From 1858 through 1870 this system was used with studded shells and it was very similar to the Armstrong system in this regard. So whether you call it the Beulieu or the La Hitte, system, it was a positive method to impart rotary motion to cannon projectiles for greater accuracy.
 
 Tracy and Mike
 
 
 Two sets of six studs provided guidance for these shells.  A version used in Japanese artillery.
 
 
 
 
 This diagram and the previous shell pic are from Wikipedia. 
 
 
 
 
 This bronze rifled gun we found on Wiki and located at Ft. McNair is rifled with the same Beulieu developed rifling system.
 
 
 
 
 The whole Ft. McNair rifled Spanish gun.
 
 
 

[gunsonwheels]

Mike & Tracy,
 
Is you last published schedule for both the 1" and 1.75" versions of this puppy still valid?  As I recall you said the 1" would be available about October of this year and the 1.75 sometime next year...??
 
GOW/George

[seacoastartillery]

Mike & Tracy,
 
Is you last published schedule for both the 1" and 1.75" versions of this puppy still valid?  As I recall you said the 1" would be available about October of this year and the 1.75 sometime next year...??
 
GOW/George

     Actually we did not write that and our schedule is precisely what it was in reply #1 when we wrote this:     A realistic schedule, providing the interest is there, is pre-production starting in Oct. 2012 and production starting in late Dec. 2012.

     The 1.75" Cannon Blanks will follow that in June of 2013 if an inexpensive, larger lathe can be located.

This is an accurate estimate with all the unknowns to be faced and illuminated.

Tracy

[seacoastartillery]

    We have been working on getting our rifled liner or sleeve product figured out for about a month now.  Not too much time for Petard target building, but we will chip away at that Special Project gradually as we have time.  First, to let you know about some changes we have decided on due to many reasons, mainly customer cost.  We have always thought that the price point for these 1" bore sleeves should be $399.00, so we have designed them, looked high and low for the best materials and have purchased efficient tooling with meeting this 1" bore rifled sleeve price always in mind.  Any less and we would not bother to make them and any more and you rifled cannon hopeful would probably not buy them.
 
      Some of the features these rifled sleeves will have are listed here:  First, they will be superbly accurate and will be guaranteed to shoot five, 1.000" Dia. cannon bolts into a tight, 3" group (measured center to center) at 100 yards, if properly installed.  They will be fitted with a strong breech plug with an excellent gas- tight seal system and correct internal radii facing the chamber area.  Seacoast Artillery will also offer a perfectly smooth, rifling free, chamber area, for no extra charge.  This will facilitate thorough cleaning between shots by allowing the sponge to rotate easily and the smooth surface will not have a place to harbor sparks from the previous shot.  The 30 inch long tube will be a superior grade, TYPE 6 DOM mechanical tube of .375" to .625" wall thickness with the tightest tolerances on roundness and straightness.  The interior will be honed by Seacoast until silky smooth.  All in all, these sleeves will allow you not only to have a really cool looking cannon, but will help you shoot some outstanding groups as well.  Remember what Col Townsend Whelan once wrote:  "Only accurate rifles are interesting!"  Our whole business is geared toward making interesting to shoot, rifled cannon!
 
      As for schedule, we will not disappoint you guys by making more predictions.  However, with the shop expansion project scrapped and the Krupp #2 project on hold for completion of the 1.0000" and the 1.7500" Bore Dia. rifled sleeves, I don't see why the development, testing and pre-production of the 1.0000" rifled sleeves couldn't be completed by summer's end.  The following series of photos will show what we have accomplished recently on this project and what needs to yet be done.
 
 Tracy
 
 
 We had to make new, smaller tube supports shown here, tiny compared to the huge Brooke Rifled Cannon support in the foreground.  Those are hardened steel wear pads JB Welded to the aluminum supports.
 
 
 
 
 A 5/8ths inch thick sleeve ready to be rifled.
 
 
 
 
Mike machined the indexing collar two days ago. It will stop the tube rotation in one of ten different positions to hold it for groove cutting.  6 robust set screws and locktight hold it on the tube.  Older collars for the 9 groove Parrott 100 Pdr. rifling and the 7 groove Brooke 7" Navy and Seacoast Rifle are stacked nearby.
 
 
 
 
 Front view showing the powerfully spring loaded, indexing spud on the left. 
 
 
 
 
 The rear view showing how the massive, clamped angle plate holds the tube from sliding back and also allows the rifling head to come partially through the breech end of the tube.
 
 
 
 
 3 weeks ago Mike machined the Rifling Head and several key features on it including the chip recess, the pivot pin hole, the wedge pin hole and the wedge adjuster bolt hole and the pinion gear mounted push/pull tube socket.  The hook cutter is not made yet.  It's width dimension will allow it to cut authentic James type rifling of 10 grooves for use as a liner in a stand off 1/3 scale 6 Pdr. Bronze Field Gun M1841. 
 
 
 
 
 We have ordered a precision ground 72" long, pre-hardened piece of 4142 steel bar, 3/4" X 1/2" for the sine bar which will replace the one shown here which was used in rifling the much shorter 7" Brooke tubes. 
 
 
 
 
 A rifled M1841 Bronze Gun.  One of the nicest shapes ever created for a cannon tube.
 
 
 
 
 The business end with 10 equal grooves and lands.  The grooves are flat cut which gives the James rifling a very noticeable and distinctive look.  Most grooves are radiused, and your eye perceives them as normal.  The James System is one of the very few with flat or faceted groove bottoms.  They look startlingly different and reflect light just as the flat cut facets of a diamond do.
 
 
 

[Doc Brown.]

Could I send you a completed barrel to be rifled? Its a 1" bore whitworth about 28" long. The barrel and breach is all finished and the breach can be removed easily. Its a sin to have this without rifling's and it would be awesome if it was rifled. PRETTY PLEASE WITH SUGAR ON TOP!

[seacoastartillery]

     Hi Doc, nice to hear from you.  A year ago when we started to think about rifled sleeves seriously, we would have said, "No".  But now, without the piles of backlog towering over us, we can at least consider it.  There are so many variables in that type of tube though, that we would require an accurate engineering drawing of it, before we would even venture a bid.  The originals had Whitworth hex rifling all the way down to the breech face, making it necessary for the cartridge case to be formed into that shape also.  We would not even consider a hex form of rifling, however, unless the customer was insistent and had the $ to develop all the special tooling required to machine that shape.  We are talking about six to ten times the normal charge for a rifled sleeve.  Not really doable unless you routinely trip over money bags you have lying about, strewn all over the place. 

     With a "normal" type of rifling form, this job could quickly approach twice the cost of a standard production rifled sleeve, because of custom features required to make it work and one-of-a-kind set-ups that gunsmithing type projects require.  Also, please note that all work on the 1.0000" dia. rifled sleeve will be done and five production units complete before we would be able to start rifling your Whitworth.  In the mean time send us an accurate drawing of your tube with every feature near or at the points of intersection with the sleeve and tube exterior, muzzle and breech. 

     While we can produce any pitch rifling and also gain twist rifling, we need to know exactly what you intend to shoot from it before the rifling form and twist can be determined.  In short, we need an accurate drawing of your projectile, before we can cut the correct rifling to spin it fast enough for reliable stabilization.

     The twist on an original 12 Pdr. Whitworth tube is very fast at one turn in 55 Inches.  We have studied these tubes at West Point, Gettysburg and at Fort Fisher and we know for sure that you have chosen a challenging project with very unique features.

Tracy and Mike

[Doc Brown.]

Seacoast here's a ruff sketch. Missing the trunnions in the picture but they are on the actual barrel to be rifled. As for the projectile what ever is cheapest and the same goes for the riling's. I don't need nothing fancy and what ever is easiest is what I would want. Thank you.

[Cannon Cocker]

   
     While we can produce any pitch rifling and also gain twist rifling, we need to know exactly what you intend to shoot from it before the rifling form and twist can be determined.  In short, we need an accurate drawing of your projectile, before we can cut the correct rifling to spin it fast enough for reliable stabilization.

     The twist on an original 12 Pdr. Whitworth tube is very fast at one turn in 55 Inches. 

Tracy and Mike

The twist rate on a Whitworth with a 1.00" "land" diameter would be between 20 and 23 by the following cyferin.  Known twist rate of 55" X 1.00" / 2.75" (12pdr Whitworth land dia.)= 20.  And also....40 (known twist rate of 3pdr Whitworth) X 1.00" / 1.7" (known land dia. of the 3pdr)= 23.  I'm guessing that if you were to measure his other guns that this ratio would be consistent.   And as long as we're playing this game, the depth of the "groove" on a 1.00" Whitworth would be 1.09".  Because....3" (groove dia. 12pdr Whitworth) X 1.00" / 2.75" (land dia.) = 1.09" 

[Double D]

Parrot Rifle sleeves?

[seacoastartillery]

     Dockholidaiy,  I will contact you offline soon.  The outside dims. you show on your tube do not appear to be a problem. 


     

   
         The twist on an original 12 Pdr. Whitworth tube is very fast at one turn in 55 Inches. 
TM

The twist rate on a Whitworth with a 1.00" "land" diameter would be between 20 and 23 by the following cyferin.  Known twist rate of 55" X 1.00" / 2.75" (12pdr Whitworth land dia.)= 20.  And also....40 (known twist rate of 3pdr Whitworth) X 1.00" / 1.7" (known land dia. of the 3pdr)= 23.  I'm guessing that if you were to measure his other guns that this ratio would be consistent.   And as long as we're playing this game, the depth of the "groove" on a 1.00" Whitworth would be 1.09".  Because....3" (groove dia. 12pdr Whitworth) X 1.00" / 2.75" (land dia.) = 1.09"     

     Cannon Cocker, we are with you almost to the end of the calculations.  Traditionally we gave used one turn in 36" for 1.000" bore dia. tubes.  this comes from our 1/6 scale seacoast rifles like the 100 Pdr. Parrott Seacoast and Navy Rifle M1861.  It had a one turn in 18 feet at the end of a gain twist rifling, so 1/6 of that is one turn in 3 feet or 36".  This twist completely stabilized steel projectiles from 1.850" long and about 6 oz to 2.300" long and about 8 oz.  However a twist of one turn in 20" or 23" would work as well.  Over stabilization is not problematic unless you are a benchrest competitor trying to eliminate the last .002 or .003 inch from your group size.

     As for the last bit about groove depth, Mike and I are at a loss.

"And as long as we're playing this game, the depth of the "groove" on a 1.00" Whitworth would be 1.09".  Because....3" (groove dia. 12pdr Whitworth) X 1.00" / 2.75" (land dia.) = 1.09" 

     Take that first sentence.  Now you cannot really mean 1.09", can you?  This is a greater depth that the original 100 Pdr. Parrott that I mentioned.  Should I ignor the 1 in 1.09", making the depth of our 1.000 bire dia. Whitworth VERY deep at .09".  Even if I divided.09" by 2 and get .045" deep, it's still a Grand Canyon of a groove.  We must be misunderstanding something here.  Please explain this section in red when you get a chance.

     Double D.,   Although we are doing the James system rifling of the one inch bore sleeves first, the Parrott will be a close second in popularity so it follows that we will follow the James with the Parrott.  However, please keep in mind that we will NOT be changing anything on our Rifling Machine to do any of the 1.000" rifled sleeves, so this means that we will be doing tubes in this size which will have 6 grooves through 15 grooves.  Some of the field artillery including the Parrott had 3 or 5 grooves, but to keep costs down ours will have 6 or more up to 15 (Type 1 James rifle).  The reason is that we cannot pull a hook cutter through a steel tube which is more than .285" wide with our manual machine.  In two or three years we might build another machine with hydraulics, but then again we may not.

     The math to support the 6 grooves is here, actually we divide the 1.000" dia. circumference by 12 which is the total number of grooves and lands which are equal in width.   1.000" X  PI = 3.1416/12 = .2618".   Since .2618" width of groove is less than .285"(our Maximum width of Groove), we can cut six grooves.

Tracy

[Doc Brown.]

Awesome! I will be shooting fleas off dogs backs at 100 yards! Hopefully.

[Cannon Cocker]

   
     As for the last bit about groove depth, Mike and I are at a loss.

"And as long as we're playing this game, the depth of the "groove" on a 1.00" Whitworth would be 1.09".  Because....3" (groove dia. 12pdr Whitworth) X 1.00" / 2.75" (land dia.) = 1.09" 

     Take that first sentence.  Now you cannot really mean 1.09", can you?  This is a greater depth that the original 100 Pdr. Parrott that I mentioned.  Should I ignor the 1 in 1.09", making the depth of our 1.000 bire dia. Whitworth VERY deep at .09".  Even if I divided.09" by 2 and get .045" deep, it's still a Grand Canyon of a groove.  We must be misunderstanding something here.  Please explain this section in red when you get a chance.

   

You're right I didn't explain the groove part too well.   What I meant is that the greater distance across the polygon is 1.09".  For a one inch bore it would be 1.00" across the flats, and 1.09 from corner to corner.  Those corners have a flat on them of course which makes it a polygon not a true hexagon which would have pointed corners. (.045") is correct though, be it a grand canyon of a groove or not.  The interesting but somewhat confusing thing about Whitworth polygonal rifling is that there is really no land per se, only groove, because once you cut into it (out .045" from center in 6 places in the case of a 1.00" bore) you only have 6 points left on the smaller flat diameter to actually call "land".  These are shown as points A on the photo included. But these only exist as reference points. There is no dimension to them because when the edge of one groove meets the adjacent groove all original "land" is gone. 

Now if you follow that, here's another interesting/confusing thing about Whitworth rifling.  On the larger bores, he (Whitworth) describes the rifling as a polygon having 24 flats or sides.  This would be accomplished by taking the 12 sided polygon in the picture and putting a flat on every corner.  So when you hear the Whitworth rifling described as a hexagon with "rounded" corners, it's not only inaccurate, it does him disservice. 

[seacoastartillery]

     Thanks, Cannon Cocker, for the clarification, I guess we were fixated on rifling conventional rifling forms.  Although we will not rifle any hex forms until we make a hydraulic powdered rifling machine, we will always keep this option open for the future.  I think what we need now is some input from those who are interested, on the types of rifled cannons in which they have an interest.  This will indicate to us at Seacoast Artillery what type of rifling forms that we should  be considering for production.

     I have brought forward the list of rifling forms which we showed in the past.  If those who are interested in obtaining a rifled sleeve or who don't mind going for a more expensive, much heavier, "Rifled Blank", would indicate what type cannon or rifling they are thinking about, that would certainly be instructive to us and would probably push the discussion into a narrower and more specific area, with appropriate focus.  It would also force us to give you specific data about the product you are proposing which, in turn, helps us by making us figure things out ahead of time.

Here is the list for your convenience:

     At this time, I would like to steer the discussion back to rifling and , more specifically, to the different forms of rifling.  Maybe a few of you will tell us what your favorite is and why or perhaps you will want to take a chance on something completely unfamiliar.  We will display about a dozen forms over the next two days and will also tell you that we would like to maybe get a consensus on one of the odd forms and make an experimental tube to shoot it for fun and to see if it can provide some decent accuracy.  Here are a few to start.
 These were drawn from books and web sites like hallowellco.com and a few from Wiki and a few from old sites for which we have forgotten the names.
 
 Tracy
 
 
 This is Armstrong Shunt Rifling displayed in our photo taken of the 150 Pdr. 8-Inch Gun at West Point.  That thing that looks like a pie plate is the end of the cylindrical chamber with a 1" radius at the bottom.
 
 








 
 
This is why making the Armstrong Shunt Rifling is so problematic.  Studded projectiles or exterior flanged ones must be used with this type of rifling in order for them to be "shunted" to the proper groove before firing.





This is the 15 groove James Type I bore again with its flat grooves to contrast with the next cannon we photographed at Phippsburg, Maine.

 
 
 
 
 


This 100 Pdr. Parrott 1861 Seacoast and Navy Rifle at Fort Popham, Popham Beach, Maine has radiused groove bottoms which you can see clearly.
 
 
 



This Gast-Renette rifling form is hard to see, but we liked the photo so we included it.  Does anybody have any info on this form of rifling?  Sounds French to us.



 
 
 
 
 This is Britten form rifling from 1862.  Remember the shell that almost changed the outcome of the famous sea battle between the Federal Ship Kearsarge and the notorious Confederate Raider, CSS Alabama.  Alabama's 100 Pdr. Blakely gun fired it's Britten shell into Kearsarge's rudder post in 1864 off the coast of France.  If it had exploded and disabled the Kearsarge, the battle might have been a Rebel victory, but it didn't and the extremely successful raider, Alabama went to the bottom of the Atlantic that day.  Below is the end of the sea shanty, a poem about this event called "Roll Alabama Roll".

A shot from the forward pivot that day 
Blew the Alabama's steering gear away 

Off the three mile limit in sixty-four
She sank to the bottom of the ocean floor"

 
 
 
]

Our 1/6 scale 7" Brooke rifling showing grooves about 70% complete.       This is modified hook-slant or triangular rifling.
 
 


 
 
A 7" Brooke rifled tube at the Washington Navy Yard with triangular rifling taken off the raider CSS Florida.
 
 



The 1/6 scale 100 Pdr. Parrott rifling that we make.




Nelson 4-Bore rifling.  My secret wish is to someday have a 2-Bore rifled barrel with which to make a replica of Sir Samuel Baker's dangerous game rifle, "Baby".  He was fond of saying,  "She spun me around like a windvane in a hurricane!"  It fired a half pound, brass, explosive shell!!!




The famous Lancaster Oval Bore.




The "Thing" below IS NOT the famous Whitworth Hexagonal form rifling.  "Hawkeye, Victor3 noticed my error of not double checking the polygon shape to make sure it had SIX and not EIGHT sides! I've seen quite a few references to this form as being "easy to cut" or easy to make.  The artillery version would be lots of things, but "easy to make" ain't one of them.  It's mechanically fitted projectiles were really good at scaring horses on the battle field due to their unique "warbling sound" and this type of rifling in the 12 Pounder Whitworth cannon was particularly good at keeping the Federal Blockade enforcing ships more than 3 miles off the North Carolina coast around the Cape Fear River mouth, because of it's accuracy, but "easy to make", No.

When I find a good image of 6 sided, hexagonal, Whitworth rifling, I will post it.Tracy




Well known Henry rifling from Scotland.




Metford rifling from England used in millions of rifles with the Enfield moniker.




From Vicksburg, Mississippi we have the famous "Widow Blakely" muzzle showing it's unique, Blakely Hook-Slant rifling.




Finally the Scott form of rifling, so widely copied in modified form.  This one was complete with flanged bolts and shells normally.





 

[Double D]

 
[/color]Metford rifling from England used in millions of rifles with the Enfield moniker.


 

 

That is not  Metford rifling, Only some early Long Lee Enfield's and Martini Metfords had Metford rifling.  It was replaced by Enfield rifling because if the erosive effects of cordite.  It was intended to minimize the effects black powder.   When the rifling was replaced by the Enfield rifling the Martinis were then were designated, Enfield  Martini's. 

[seacoastartillery]

     Changed back in Reply 112.  Thanks for pointing that out.  And if anybody wants Metford rifling for their cannon, we will put them at the end of the list, giving them a special quote for the extra tooling charges.

Mike and Tracy

[seacoastartillery]

     Recently Cannon Cocker brought the subject of less clearance between the I.D. of the "host cannon" and the O.D. of the rifled sleeve to be inserted.  The installer has to be very careful here as BIG problems can appear at the worst possible time.  On the white board we have two different scenarios, one has a reasonable amount of clearance, .020" all around and the other doesn't, at only .010" all around.

     In both cases, the installer had only a vague idea of the straightness of the cannon's bore enlargement which was drilled out to accept the rifled sleeve.  In one case the installer thought less is better and made the cannon bore 1.770" Dia., only .020" more that the sleeve O.D.    .010" clearance all around was not enough for a straightness of .025" on the cannon bore axis and .003" on the sleeve axis.  If your clearance between the two is not more than .028", you are in trouble.  The bottom sketch details what happens when an interference condition exists and hydraulic power pushes the sleeve in anyway.  Now you have a curved, rifled, sleeve and a huge mess to disassemble and do over.

     The installer of the upper cannon bore and sleeve was similarly in question about the cannon bore's straightness, but he allowed twice as much clearance by boring the cannon's tube out to 1.790" Dia. and got his sleeve inserted without bending it.  Both of these installers knew enough to have a copper vent liner ready for installation after vent drilling and tapping.

     The curved portion of the freehand sketch leaves something to be desired, but I bet you understand the concepts it represents.  Also included is a pic of the 1/2" X 3/4" 4142 Prehard steel bar which was just delivered.  We will turn this six footer into a really nice sine bar after we  inspect it on the surface plate and trim it to 40 inches.

Tracy


The OOPS! and the Ahhhhh, it worked!  sketch.






The Rockwell 30 'C' scale 4142 bar due to be a new sine bar on our rifling machine.

[Cannon Cocker]

     Recently Cannon Cocker brought the subject of less clearance between the I.D. of the "host cannon" and the O.D. of the rifled sleeve to be inserted. 

20 thou all around seems like a good rule of thumb, and I wouldn't advise pressing any sleeve into a bore without a dry fit first which would show any mechanical resistance.   

[seacoastartillery]

     Mike and I agree with Cannon Cocker, a dry fit of the rifled sleeve into the cannon's enlarged bore is a VERY good idea and could save the installer enormous hassles and much grief.  DRY FIT !

     Seacoast Artillery will pack the sleeves in a thick tube and with excellent dunnage so they won't be bent in shipment.  Ask anyone who bought a Krupp Howitzer from us if we know how to package to prevent damage!!!

Mike and Tracy

[seacoastartillery]

     Over the past week and a half Mike finished the refinement of the James System rifling cutter and then we did a little math to set the sine bar at the correct angle for a twist of one turn in 42 inches.  Other than a flat, rather than radiused groove bottom, it's really hard to tell this rifling form from that of Parrott rifling.  Anyway, below are several pics of the 10 groove, thick-wall rifled sleeve without a breechplug as yet.  We can trim the wall thickness down to any thickness the customer wants, 1/4 inch or over.  The one we are holding is out first prototype, so it will stay thick for all kinds of experiments, most aimed at determining this rifling form's accuracy.

     Seacoast was closed today because of a air conditioner calamity.  The bearing screeched momentarily then seized up.  Being 95 deg. outside, the temp. in the machine shop rose slowly until it was quite sticky, then it was time to go to our mechanical tubing supplier to get more mortar tubes. We got enough to do 8 coehorn style mortars in the large Bush's Baked Bean can size, 4.25" Dia..  Filled with concrete or mortar mix those cans will become 5 Lb. pallet destroyers.

Mike and Tracy


Mike was smirking, so I told him to cut it out.  This was the result!  A heavy duty rifled sleeve you could use as the basis for a built-up gun, if you wished to do so.




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.




The muzzle has not been crowned yet.  This is a rare look at rifling right off the rifling machine.  Mike says he thinks this barrel is about perfect.  He says this steel, 1026, cuts like butter compared to the pre-hardened, Rc 30, 4150 that we normally use in our premium seacoast artillery.

[Cannon Cocker]

   
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.

That's a work of art!  Looking down a nice shiny new rifled barrel is a beautiful thing. 

How did you determine the parameters for stabilization in your statement above?  Especially when you included projectiles (zinc and lead) that have huge specific gravity differences. 

[seacoastartillery]

     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