Author Topic: 40 MM Rifled Breach Loader (Read 15913 times)

moose53 · « **on:** May 13, 2011, 06:53:55 PM »

I have a 40 MM Rifled barrel 31.5 in long . It is to short for most uses, so I am using it as a base to try several ideas on how to utilize barrel remnants. Finished the breach tonight , it is 2.75in OD x 4in threads . The threads are buttress form, 2 pitch 4 threads per in.

SLEEPY BEEPER · « **Reply #1 on:** May 14, 2011, 05:42:34 AM »

AAAH, Your killing me here. 40 MM X 31.5 inch is perfect for a full sized breach loading Hughes cannon.

moose53 · « **Reply #2 on:** May 15, 2011, 03:17:53 PM »

Yes I tend to forget how hard it is to get 40mm barrels now. I am trying to use the last one I have the best way I know. The breach block is blanked out ready to thread for breach screw . Enclosed is a working drawing to show the internal shape . The front is still being figured ,so it is not drawn out.

Double D · « **Reply #3 on:** May 15, 2011, 03:32:08 PM »

So Moose53 which pre 1899 breech loading gun are you going to make?

moose53 · « **Reply #4 on:** May 15, 2011, 05:14:44 PM »

I really like the Whitworth Rifle so I will keep as much of it as I can . The improvements made between Civil War and Spanish American War are to good to pass up so I will use the breech of a 3.2 Field Cannon model 1885 without cutting the interrupted threads . Not set up for cutting internal interrupted threads. The problem with the Whitworth is the threads are directly over the powder , a weak point . The 3.2 is a much safer design.

moose53 · « **Reply #5 on:** May 16, 2011, 07:11:54 PM »

Finished threading the breach today . Next step will be to fit the barrel , I am figuring this out as I go so hope not to run into any surprises

keith44 · « **Reply #6 on:** May 17, 2011, 06:22:49 AM »

Here's a 40 I found on you tube don't know if he says anything useful for ya or not, but he does shoot it a few times.

http://www.youtube.com/watch?v=ScNxzy1fRZw

enjoy, and good luck with yours. They look fun.

moose53 · « **Reply #7 on:** May 17, 2011, 07:35:28 AM »

Thanks, yes that is a good example of utilizing a short barrel. He could probably do better on his projectile, but the barrel looks good.

KABAR2 · « **Reply #8 on:** May 17, 2011, 07:36:02 AM »

that's a Cannonmn video, Ed is a buddy of his and acts as a helper
in many of his video's he does some strange things with 40mm projo's.....

By the looks of things I'll have my Whitworth project going very soon,
also a 40mm.

Cannoneer · « **Reply #9 on:** May 17, 2011, 09:03:26 AM »

moose53,
Thanks for opening this topic and sharing your build, I've been watching it develop with a lot of enthusiasm. For me these documented build in progress threads are some of the most interesting on the forum.

keith44 · « **Reply #10 on:** May 17, 2011, 02:11:32 PM »

I agree, even if I cannot add much to the conversation, I enjoy the build posts.

Cannoneer · « **Reply #11 on:** May 17, 2011, 10:30:43 PM »

For anyone wondering what that contraption was on the bench next to Ed's 40mm breech loader, it was cannonmn's infamous 32 barrel bp machine gun.

http://www.gboreloaded.com/forums/index.php/topic,177367.msg1098846773.html#msg1098846773

moose53 · « **Reply #12 on:** May 18, 2011, 03:48:30 PM »

I successfully threaded the barrel today . It was interesting holding tolerance on the 40 mm as it wanted to act like a piece of spaghetti. With a bull center and cathead and steadyrest vibration and tolerance were handled nicely. It is starting to look like a cannon. Threads are buttress and 10 threads/in.

seacoastartillery · « **Reply #13 on:** May 19, 2011, 12:07:38 PM »

Moose53, using the photo of the Model 1885 U.S. 3.2-Inch Field Gun provided below can you tell us basically which features you will be using and which ones will not be used. For example, will you be using the De Bange style obturator for your breech- loading bag gun? Will your vent be radial as was the Model 1885, or will it be axial, through the center of the obturator spindle, as was the Model 1890?

Mike & Tracy

The Model 1885 Breech via: http://www.fieldsofthunder.com/content/cannons.html

armorer77 · « **Reply #14 on:** May 19, 2011, 01:54:30 PM »

Do you have a Shaper ? That is the only machine within the reach of most folks to cut an internal interupted thread . I built a small one several years ago . I may have to dig it out and dust it off . Interesting . Armorer77

moose53 · « **Reply #15 on:** May 19, 2011, 06:00:59 PM »

Mike & Tracy thanks for the photo of 3.2 field gun , its nice! The vent will be through the center of the obturator spindle and I will be using a DeBange style obturator . What I had in mind was a Whitworth with a internal breech instead of a cap,and I want to use the Whitworth handle , think its cool. Had first barrel fit today , almost ready for first fire. Armorer77 don't have a shaper and haven't come to the mental necessity of interrupted threads

dominick · « **Reply #16 on:** May 20, 2011, 02:45:24 PM »

Moose53, If I remember correctly, didn't you make a few Whitworth barrels a while back?

moose53 · « **Reply #17 on:** May 20, 2011, 05:07:07 PM »

Good memory , yes I made three 40mm Whitworths. http://www.gboreloaded.com/forums/index.php/topic,93883.0.html The breech set up always bothered me with the powder chamber as thin as it was under the threads . Its been relatively resent that I figured to screw the barrel into the breech , so far it looks like a much better way to go.

moose53 · « **Reply #18 on:** May 21, 2011, 07:50:27 AM »

Finished the detail on the 40mm powder chamber. The 2 deg per side 4 deg total taper is for the obturator. The straight sided powder chamber will accommodate the aluminum foil powder cartridge . The over size powder chamber will accommodate any possible increase in powder charge while letting smaller charges be augmented by inert material.

seacoastartillery · « **Reply #19 on:** May 21, 2011, 11:05:11 AM »

Quote from: moose53 on May 21, 2011, 07:50:27 AM

Finished the detail on the 40mm powder chamber. The 2 deg per side 4 deg total taper is for the obturator.

I believe I understand your intent is to give up the 'Beef Tallow impregnated Asbestos Pad' which lies in back of the Obturator Spindle's rear shoulder in DeBange's Breech design. If that is true, then will the 2 degree taper you show in your drawing mate precisely with a 2 degree taper machined on the surface of your breech block, starting at the point of tangency where the rear edge of the mushroom cap meets the forward edge of the breech block's 2 degree taper? Will these two surfaces provide the gas seal or will there be some other accommodation?

Tracy and Mike

A DeBange breech used in 1893 on the British 6" B.L., Mark III. From Wiki Commons, draftsman unknown, this drawing clearly shows the major parts of the Debange system breech, the interrupted screw-locking block, the floating mushroom cap obturator spindle and the asbestos pad under the spindle's mushroom head. Upon firing this pad, lubricated by the beef tallow component, squeezes outward to seal the breech, preventing hot gasses from escaping.

moose53 · « **Reply #20 on:** May 21, 2011, 01:37:57 PM »

The Obturator design used is one I used with my previous Whitworth cannons . With a recreational rate of fire it never gets hot enough to cause a problems and it works 100%. Very easy to make and should have a life expectancy the same as the cannon. It consists of a rubber block with a vulcanised 1/4in plate backed up by a stainless steel plate, all shaped to fit the taper . It is attached to the breech screw with a stainless through bolt drilled for a flash hole . Attached is a photo of the Obturator used in the Whitworth cannons , the new one will have the bolt extend through the breech screw .

seacoastartillery · « **Reply #21 on:** May 21, 2011, 03:32:21 PM »

Is the rubber plug between the two metal plates expanded by drawing one plate toward the other with the central bolt, squeezing the rubber out to make a seal? Or, does it get sqeezed by the concussion of firing?

Tracy

moose53 · « **Reply #22 on:** May 21, 2011, 04:02:15 PM »

It happily works out to do both. The fit can be precisely adjusted with the bolt and the pressure of firing seals it completely.

Frank46 · « **Reply #23 on:** May 21, 2011, 05:57:47 PM »

Moose, ever given thought to use valve packing for your sealing?. Back when I wore a uniform I stood watches in the shaft alley known as the thrust block. It was the where the propeller shaft went through the hull. The huge packing assembly used a combination of lead foil wrapped flax impregnated packing and just regular flax impregnated packing. This stuff was about 1.5" thick. Although you would probably use a smaller size. The packing when compressed used to drip some of the flax oil that the packing was saturated with. When the shipyard had removed all of the packing with packing hooks (fun job) it was then repacked with fresh packing. you did have to keep some sea water leakage to help lubricate the packing though. It did have to "run in" before you you started adjusting the packing glands. We used to measure the opening on the packing gland to insure it was evenly compressed all the way around. How are you planning to fit the trunions? Mill pockets or install a sleve with the trunions welded in place and weld the sleeve in place. Frank

moose53 · « **Reply #24 on:** May 21, 2011, 06:24:35 PM »

The vulcanized rubber is so simple and effective,I never looked for another material. The trunnions will be welded to a sleeve and the sleeve sweated to the barrel . It is not a good idea to weld on a modern artillery barrel. The one disadvantage of sweating a sleeve on a modern barrel is it will collapse it slightly . Not sure if it really is detrimental to accuracy or not.

GGaskill · « **Reply #25 on:** May 21, 2011, 09:36:04 PM »

The one disadvantage of sweating a sleeve on a modern barrel is it will collapse it slightly . Not sure if it really is detrimental to accuracy or not.

It can't help. Make a lead lap and lap out the constriction.

moose53 · « **Reply #26 on:** May 22, 2011, 06:05:37 AM »

Thank you ,that would be a good fix . I hadn't really considered that before. I found out about the constriction by driving a brass plug down the barrel . From what it felt like the constriction was .0005-.001 in so not very much.

keith44 · « **Reply #27 on:** May 22, 2011, 12:14:24 PM »

from my experience with rifles, that would be enough to deform the projectile slightly more at one or two points radially and as the procectile passed through the crown of the muzzle it would likely not cleanly and evenly "release" the projectile, rather it would be as if the barrel needed to be re-crowned.

moose53 · « **Reply #28 on:** May 22, 2011, 12:25:46 PM »

So the constriction could very well be the cause of the mysterious fliers I am getting

keith44 · « **Reply #29 on:** May 22, 2011, 01:05:20 PM »

it's one possibility. depending on what you are shooting, muzzleloaders have a "special" set of variables that fixed ammo guns do not encounter. However a constriction about mid-barrel can wreak havoc on both.