Author Topic: Does the Chamber Area of Modern Replica Rifled Artillery Have Rifling? (Read 1305 times)

seacoastartillery · « **on:** January 15, 2012, 06:43:05 AM »

Does the chamber area have rifling or not on replicas which are built from steel tubes and breech plugs OR cast iron tubes and inserted rifled sleeves? If so, how is this accomplished? Any help would be appreciated.

Mike and Tracy

Double D · « **Reply #1 on:** January 15, 2012, 07:31:24 AM »

Probably depends on who is doing the replica. The Original drawings I have for the 3 inch Ordnance rifle, 3 inch Parrot Rifle and the 6 PDR rifle M-1841 pattern all show a smooth chamber. How that transition from rifling to smooth bore was accomplished in a blind hole is not detailed in these drawings.

I would be simple enough to ream a liner and install breech plug. I would think you would want to have a tapered transition for smooth to rifling so as not to catch smouldering debris.

gunsonwheels · « **Reply #2 on:** January 15, 2012, 09:40:05 AM »

I have a 1/2 scale ordnance rifle made from a 40mm bofors barrel and did NOT clean the rifling out of the chamber area... so the rifling extends all the way down to the threaded plug face.

I've been thinking of machining a new plug that would have a cup and sleeve to extend up the bore wall and would be smooth. Combined with the new plug would be machining out the rifling plus some relief and a taper of the rifling down to a smooth seam between barrel and front edge of the plug's chamber/cup wall. The result would also improve the shape of things at the bottom of the bore so as to provide a greater absence of places to hide embers.

As DD says "probably depends on who is doing the replica" and since joining the board I have become more conscious and more conscientious about rounding the bore bottoms... whether the fab is solid or with a removable plug.

seacoastartillery · « **Reply #3 on:** January 15, 2012, 07:05:15 PM »

Double D., Thanks for the info on those drawings. Too bad they don’t have a close-up of the chamber transition to the rifling. It would be very nice to have a definite answer on whether the rifling grooves went under the chamber/bore surface OR if the chamber was somehow smoothed while being enlarged to groove dia. which would require a tapered transition to be machined on the bottom end of each land. While this would be fairly simple to do on a modern sleeve, it would be almost impossible to do back during the Civil War, especially in the field as the Eason Bros. of Charleston, South Carolina actually rifled large seacoast guns where they were mounted at the forts. Their “traveling rifling machine” actually clamped to the tube, itself, and did a fine job we’ve read.

Gunsonwheels, If I interpreted what you wrote correctly and represented your description of what you want to do accurately in Fig. 1, then Why is this type of breech plug and chamber area superior to the more conventional one shown in Fig. 2?

We did get some information on how one current maker and the original Parrott cannons were rifled when we talked with Bruce and Bernie Paulson at their shop in December of 2006. They patterned their rifling machine after the one Parrott used at his West Point Foundry in Cold Spring, New York where his rifling mechanics “blind hole rifled” the hole saw cut and reamed bore. Parrott’s machine and the Paulson’s had a unique feature that cammed the hook cutter inward toward the center of the bore at the end of the stroke. With a machine designed like this you can set the chamber “end” of the rifling anywhere you want it. We suspect full depth rifling, .100” deep, ends right under where the brass or wrought iron sabot lies when loaded against the powder charge. This is so, when expansion of the sabot occurs upon firing, engagement of the grooves can happen immediately.

We must emphasize that we have no clue how any current maker plugs their rifled sleeves or whether any reaming of the breech end is done during that process.

What is a little confusing here is the chamber to bore/ land diameter relationship in the blind hole muzzle loaders and the same relationship within the typical breech loader. The projectiles of the typical breechloader use a driving-band of copper or, these days, hard nylon which is cut by all the sharply tapered land ends simultaneously to impart rotation to the projo. The chamber MUST be at or near groove dia. for this arrangement to function as it does.

Is there someone out there familiar with full size replica Civil War rifles, Parrott, Ordinance, or James rifles who knows for sure if the Chamber is rifled or not and if so, how the Chamber transitions to the Rifling? Is the rifling land dia.(bore dia.) the same or smaller than the Chamber dia.?

Thanks for the thoughtful responses, gentlemen.

Mike and Tracy

gunsonwheels · « **Reply #4 on:** January 15, 2012, 07:33:34 PM »

The sketches accurately depict my efforts as well.

The first is what I described verbally except the threads end below the plug face and a running/sliding fit sleeve extendeds up inside the barrel and butts where the rifling has been relieved.

Sketch two is an alternative I have also drawn which would be enabled by simply turning the cavity in the existing plug face and then relieving the rifling by boring the chamber area to the rifling goove diameter and then that section would transition into the fully rifled area of the tube by tapering the rifling from nothing (0.000") to the full land height. Obviously sketch two would be way less additional work and considering I have nine unfinished ordnance projects and a disabled wife to care for it will probably get the nod over the new plug version.

I understand the Parrot concept but other than that how you could do the relief without having access to the breech end... I don't have a clue...

Cannon Cocker · « **Reply #5 on:** January 15, 2012, 07:38:24 PM »

My 2.25" mountain rifle has a steel liner made by Ken Kurdt who does a lot of work for civil war cannon barrel makers. It has a welded breech plug (slightly concave on the inside) and the first inch or so of side wall is smooth before the rifling starts.

Double D · « **Reply #6 on:** January 16, 2012, 02:37:39 AM »

With a liner all you need is a "big neck and throating reamer to taper the lands to make a chamber.

In a blind hole you would need to have a way too taper the grooves up into the bore at the bottom

Cannon Cocker · « **Reply #7 on:** January 16, 2012, 01:42:00 PM »

[quote Is the rifling land dia.(bore dia.) the same or smaller than the Chamber dia.?

Mike and Tracy,

I just put a bore light down the mountain rifle and also a tape measure. The rifled liner has a reduced bore (smooth) by maybe .1" or less for a half inch from the back. I can catch the tape measure on it before it skips off and up to the end of the bore a half inch farther. The rifling is 3 saw tooth or ratcheted grooves as was the original.

onegreatshot · « **Reply #8 on:** January 17, 2012, 07:30:50 AM »

I would love to see gunsonwheels BOFORS cannon

. The picture I have in my minds eye is a mean looking cannon

VA Rifleman · « **Reply #9 on:** January 17, 2012, 02:09:04 PM »

Quote from: seacoastartillery on January 15, 2012, 06:43:05 AM

Does the chamber area have rifling or not on replicas which are built from steel tubes and breech plugs OR cast iron tubes and inserted rifled sleeves? If so, how is this accomplished? Any help would be appreciated.

Mike and Tracy

My 2.25" Mtn Rifle liner has a gain twist that starts well after the powder chamber. Looks like more then enough room to easily house the charge. I like this design as a smooth chamber has less voids to house smoldering debris. I have a set of plans for what is known about these rifles and can check those to confirm the length of the rifled area on the originals. As DD suggested earlier, there is a smooth transition from the chamber / bore dia to the start of each grove.

Cannon Cocker · « **Reply #10 on:** January 17, 2012, 02:50:29 PM »

My 2.25" Mtn Rifle liner has a gain twist that starts well after the powder chamber. Looks like more then enough room to easily house the charge. I like this design as a smooth chamber has less voids to house smoldering debris. I have a set of plans for what is known about these rifles and can check those to confirm the length of the rifled area on the originals. As DD suggested earlier, there is a smooth transition from the chamber / bore dia to the start of each grove.

Rifleman,
You have a gain twist? Mine has one twist in 10 feet which was supposed to be the same as an original. What is yours? Also, very interested in what plans you have on the gun as I have never been able to find much info on it.

seacoastartillery · « **Reply #11 on:** January 18, 2012, 07:42:26 PM »

Cannon Cocker and VA Rifleman, Thanks for your excellent information. Please look at the photo of my marker board sketch. Is this the configuration of your Confederate Mountain Rifle Chamber and Rifling intersection? This is the way Parrott rifled his cast iron cannon large and small, all with gain twist rifling, by the way. This is also the way the Paulson Bros. told us they rifled their sleeves. Both makers had a radiused end to the groove which broke out at the "Bore Dia. Surface" which is the "Rifling Land Surface" too.

Tracy

Please note that the sketch shows a red dashed line for the rifling groove bottom and that the groove depth IS NOT shown proportional to the sleeve thickness.

Cannon Cocker We did some basic calculations today and came up with a possible explanation for your description of the unusual rifling to chamber intersection and your belief that the smooth chamber area is .10" or slightly less in dia. than is the bore.

First, your bore is 2.25" dia. and this means that it's circumference is 2.25 X 3.1416"= 7.0686". If each land (3X) and groove (3X) are of equal width, then each groove is 1.178" wide. We checked all 7 of our tape measures. They have blades and hooks at the end which are from .25" wide to .75" wide. All of these will easily glide down your bore ending up at the bottom entirely within one of the three grooves. It is simply a theory, but is it possible that, when you pushed the hook slowly into the chamber area, that you saw the shiny, highly reflective in your flashlight's glare, rivet, uppermost on the hook of your tape, RISE as it slowly came up and out of the wide rifling groove to the smooth chamber section with the same diameter as the bore?

Respectfully,

Tracy and Mike

Double D · « **Reply #12 on:** January 19, 2012, 06:41:01 AM »

Tracy!!!

Get ye to college and take that drafting class. Don't be afraid, you can do it. I did it!

If I can do it with my limited experience in this field, someone with your knowledge and skill will just breeze right through. If I were down there I would hold your hand and walk you to school the first day, so you wouldn't be afraid.

I have been trying to convince Tracy to do this for months. He's a Vet and a senior citizen and probably qualifies for reduced or free tuition.

Moderators, if you interpret this as flame intended to humiliate and embarrass Tracy, you may be right....I am trying to give him a Larry the cable guy cyber boot in the back side to Git'er done!!!

Cat Whisperer · « **Reply #13 on:** January 19, 2012, 06:53:47 AM »

Hey! I LIKE them carrying on the tradition of P-P 0-1 drafting!

Cannon Cocker · « **Reply #14 on:** January 19, 2012, 09:34:22 AM »

Quote from: seacoastartillery on January 18, 2012, 07:42:26 PM

Cannon Cocker We did some basic calculations today and came up with a possible explanation for your description of the unusual rifling to chamber intersection and your belief that the smooth chamber area is .10" or slightly less in dia. than is the bore.

First, your bore is 2.25" dia. and this means that it's circumference is 2.25 X 3.1416"= 7.0686". If each land (3X) and groove (3X) are of equal width, then each groove is 1.178" wide. We checked all 7 of our tape measures. They have blades and hooks at the end which are from .25" wide to .75" wide. All of these will easily glide down your bore ending up at the bottom entirely within one of the three grooves. It is simply a theory, but is it possible that, when you pushed the hook slowly into the chamber area, that you saw the shiny, highly reflective in your flashlight's glare, rivet, uppermost on the hook of your tape, RISE as it slowly came up and out of the wide rifling groove to the smooth chamber section with the same diameter as the bore?

Mike and Tracy,

It is is not the possible explanation you suggested. I'll explain why and try to describe the bore in different terms. The saw tooth rifling with only 3 grooves makes the bore look like it's almost a smooth bore with 3 widely spaced narrow grooves rather than a typical barrel that has almost even land and groove distribution. So when looking down the bore there is no doubt about whether you are on a land (probably 95% of the interior surface) or in a groove. I have determined that the 1/2 inch long reduced chamber area is the front edge of the radius plug and the rifling starts immediately after that. I can see it clearly. In order of diameters it most definitely goes from largest to smallest: bottom of the grooves, interior of the bore, then chamber/end of plug. This arrangement seems workable in that the vent goes through before the rifling starts, the charge always takes up more room than the "chamber" and there is no need to have a throat or rifling ramping up to the lands because it is not a breech loader.

VA Rifleman · « **Reply #15 on:** January 19, 2012, 12:58:48 PM »

Quote from: Cannon Cocker on January 17, 2012, 02:50:29 PM

Rifleman,
You have a gain twist? Mine has one twist in 10 feet which was supposed to be the same as an original. What is yours? Also, very interested in what plans you have on the gun as I have never been able to find much info on it.

Hi Cannon Cocker,
Yup a gain twist. I have been working on a new mold and wanted to get a better idea of my bore’s properties so I used a degree wheel attached to my ramrod that I slightly modified with a brass screw to engage the rifling and measured the rotation of the degree wheel every 2 inches. The 1st 2 inches of rifling worked out to be 1 turn in 600 ft. The twist gets progressively faster till the last 4 inches which is steady at 1 turn in 10 ft. Ken K made this liner with the tube built by James West. For the non NSSA folks, James and Robby West have shared the honor of being division artillery inspectors for the NSSA. These guys are the A team.
I have the Antique Ordinance plans for this gun. Number 56 if I remember right. They did not show the length of the rifling which I wanted to get for the Sea Coast folks. Lacking this, I measured the "free bore" in the powder chamber and it is 1.78 calibers in length or 4 ". A 75 gram charge gives the appearance of being a square charge but some of the length is the foil at the end. Anyway, this charge length allows about 2 inches of the projectile to be seated in the non- rifled area. Our NSSA charges are much lighter than the service loads back in the day.

Mike and Tracy,
I can’t see your pictures due to the internet filter settings at this work computer, so forgive me if I can’t comment on your pics.

Cannon Cocker · « **Reply #16 on:** January 19, 2012, 03:06:03 PM »

Rifleman, That's very interesting as my liner is also made by Ken Kurdt and seems to be very different (see my last post). Also, I assumed my gun was a straight 1 twist in 10 ft (which is what I ordered). I also noticed that you shoot a pellet style projectile that looks like mine. Mine is from Bill Anderson. Your 75 gram charge is 2.65 oz. and I shoot 2.5 oz. I've got the Antique Ordnance plans and you're right about them saying nothing about the chamber configuration.

seacoastartillery · « **Reply #17 on:** January 19, 2012, 03:42:38 PM »

Thanks for the boot towards modern drafting, Double D. However, I will have to join a Yoga group to get my exercise if I just sit in a chair and stare at a monitor for more hours. The way I get these quick sketches or in-process partial drawings requires some real contortions. Just to draw these quick sketches for this thread I had to thread my feet into ankle-breaker territory, ( Mike had a row of 100 pound Brooke tubes in wooden cradles) exactly where I had to stand, then to get the photo I had to lean way back over our little shaper and yet put one arm up over the engine hoist also in the way and, and at the same time, stretch way, way up with the camera and flash unit to get the "bright spot" off of the drawing, itself. Thanks DD for spurring me on. I will look into a training program. Are you sure that they will attempt to train a fellow who is really famous with his grandson for knowing all those dinosaur names, because he used to see them grazing in the fields while walking to grade school?

Cannon Cocker, I get it now and I have seen that form of rifling before. That description is very clear and I understand what you have now. Thanks again and your comment about, " there is no need to have a throat or rifling ramping up to the lands because it is not a breech loader" shows Mike and I that you totally understand what we were trying to get at with the "below the surface of the bore dia. rifling grooves". Thanks again. Your rifling can be called ratchet or hook-slant, but we now understand it's form and you're description indicates that it is quite different that either the Blakely or Brooke pattern. Thank you for taking extra time to describe your cannon's bore so clearly.

VA Rifleman, Can you see it now? Can you see it now? How about now?

Thanks for the numbers and another very clear description. I am speculating, but there is obviously expected to be some movement of the projo, at least two inches, before peak pressure is achieved which flairs out the sabot into the grooves. It has been our experience that a slight increase in powder charge from what is expected, is sometimes necessary to get this engagement of the rifling done. We followed standard safety protocol by starting low and gradually going up to a charge which indicated engagement had occurred, because of the dramatic effect on accuracy. The results of those extensive experiments are displayed in one of the photo galleries on our website. Thanks again for sharing the details of your cannon's bore with us.

Mike and Tracy

Cannon Cocker · « **Reply #18 on:** January 19, 2012, 05:45:23 PM »

Hook slant, saw tooth, ratchet, early Brooke, Scott, Blakely, triangular. So many names....so few guns with it.

Double D · « **Reply #19 on:** January 20, 2012, 06:56:16 AM »

Quote from: seacoastartillery on January 19, 2012, 03:42:38 PM

Thanks for the boot towards modern drafting, Double D. However, I will have to join a Yoga group to get my exercise if I just sit in a chair and stare at a monitor for more hours. The way I get these quick sketches or in-process partial drawings requires some real contortions. Just to draw these quick sketches for this thread I had to thread my feet into ankle-breaker territory, ( Mike had a row of 100 pound Brooke tubes in wooden cradles) exactly where I had to stand, then to get the photo I had to lean way back over our little shaper and yet put one arm up over the engine hoist also in the way and, and at the same time, stretch way, way up with the camera and flash unit to get the "bright spot" off of the drawing, itself. Thanks DD for spurring me on. I will look into a training program. Are you sure that they will attempt to train a fellow who is really famous with his grandson for knowing all those dinosaur names, because he used to see them grazing in the fields while walking to grade school?

You, will be the dinosaur...

Quit looking for excuses and do it!!!