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Discussion Starter · #141 ·
Another update on the scratch made pseudo 37mm.
I have the traverse mechanism figured out, and as good as I can get it. I’m using a starter bendix and flywheel ring gear for traverse gears. The actual worm gear mechanism came from an electrical sub station for raising and lowering transformers. It took some significant modification to get it to work. It doesn’t have the same appearance as the original, but I was not ambitious enough to machine a copy when this works. I tried a VW steering gear box, but it didn’t work.
Either way, I had to stray from the original. As such I had to cut the armor different than the blue print to fit that worm gear I found/adapted.
Also had to use some creative license to get the quick traverse (gear disconnect) to work.
I had to depart from the original design a bit, but it works.
Still lots of welding and polishing to do.
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Discussion Starter · #142 ·
Next on the “to-do” list was to thread the barrel to fit the breech. The original barrel measured 4.75” for the major diameter at the breech. I wasn’t going to to buy a piece of 4.75 DOM and turn off 75% of the diameter and weight.
I did buy a piece of 3.25 DOM, which is the average major diameter between the rings on the recoil sled. I did turn a solid steel sleeve to mimic the chamber swell at the breech. It hides the actual diameter of the barrel while looking like the original.
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After that I decided to make the barrel nut. I did that before tapering the barrel due to the fact that I figure it to be easier to test fit the barrel nut while the barrel is still in the lathe.
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Next is to taper and contour the barrel then thread it for the barrel nut.
 
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Discussion Starter · #143 ·
It took four days to turn the barrel. Before work, during breaks, during lunch, after work...
Not sure how many hours total.
A lot. Maybe 8 give or take.
Anyway, I got it tapered and the muzzle swell.
37mm is 1.45 inches. I ordered 1.5 DOM so I extrapolated the difference to reflect in the outside diameter at the muzzle.
I then threaded where the barrel nut goes. 12 threads per inch. 3.25”
It looked so good that I had to mock it up on the carriage.
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Discussion Starter · #144 ·
I have decided that since I have gone this far that I am going to submit a form 1 and complete this as an NFA DD.
Especially since no one that I have talked to can tell me whether or no it will be considered a DD if I complete it.
At this point it has NO chamber for any known fixed ammunition and has a 1.5" steel rod welded into the breech end of the bore. On top of that the breech ring is incomplete and there has been no breech block machined. Right now it is a 900lb paperweight.
I had given thought about making it a breech loading black powder cannon. Fired by a .22 blank used in powder actuated hammers.
That would make it kind of like a big Civil War Sharps rifle. Insert projectile, insert powder bag, close breech, prime, and fire.
I asked a class 7 SOT and he said it depended upon the agent who looked at it. I asked an ATF agent, they said they would have to ask the NFA folks. I sent the Firearms Technology branch a letter with detailed descriptions, measurements, and excerpts from the NFA rules to see IF it would be considered a DD.
I got a very polite reply that they could not make a determination through descriptions, drawings, blueprints, photos, etc. The firearm would have to be sent to them in WV for testing and that they were not responsible for any damage that may occur during testing. Also the rules say that if it was determined to be a DD I could lose possession of it and it could be destroyed.

I've got too much time in it for that. I would cry for sure.

For me $200 is nothing to sneeze at, but it is better than legal issues and/or losing a project that I have worked on for 7 years (off and on).

The hang up is that the bore is over .50 inches. I imagine they could say it met the criteria for a DD, even though it would fire using pre 1898 style loads and ignition sources, i.e no fixed ammunition. Unless I cross drill through the bore and put rods through it for blank fire only, but what's the fun in that? I am not sure that I will live fire it more than a few times ever. Even then it will be by remote means from a covered place. However, If I decide that I want to shoot it, then by God, I want to be able to shoot it. 95% of what it will shoot will be blanks though. I am just not willing to remove the possibility of live fire.

If I am going to build this to fire then I about as well rifle this barrel so I can hit what that really nifty sighting mechanism that I made is aiming at. Soooooo I have gone and gotten my fingerprint cards, and getting the photos printed. While I am waiting on the Form 1 approval, I think I am going to make a contraption to rifle this barrel. It is supposed to have 1 turn in 25 calibers. So 1.5 inches times 25 is one complete rotation every 37.5 inches. I can do that. It is supposed to have 12 grooves. I can do that. What I am seeking suggestions on is how to machine an adjustable carbide cutter that I can drag down this 6 1/2 foot long barrel and cut the rifling. It'll take a whole Saturday or possibly weekend to cut, index 12 times, then adjust the cutter and repeat until the grooves are 1/16" or 3/32" deep. I am thinking that the groove needs to be at least 1/8" wide.

Along the way, I am also going to have to machine a lead mold for conical point hollow base projectiles alone the lines of a Civil War Enfield bullet. I am not sure that the rings from a Minie' Bullet (Minnie Ball) are necessary. I'll cross that bridge when I get to it.

Again, this is one of those projects that I often look at and wonder "what was I thinking?"

Anyway, any suggestions on an adjustable cutter to cut rifling grooves about 1/8' wide in a 1.5' diameter bore that is 78" long?
 
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