Breech face fouling trouble

[M. De Land]

Actually the military has used 4150 since it was developed, Simply because it can he shot at very high temperatures with out failing. I think you will find the information in Hatcher’s book of the Garand. I have shot barrels till they were incandescent and have seen others done the same. Back when I ate a lot of C-Rations and slept in the mud. The 45 ACP pistol barrels were, SFAIK made of mild steel. And at least some civilian barres still were at least until the stainless craze took over.

Yes, I have Hatcher's book and will check but was under the impression that Springfield and Enfield barrels ( WWl not WWll)
were all 10 series steel . P.O. Ackley's book is a real treasure trove of information on military steel used. 4140 was developed in the 1920's so it makes perfect sense it would be used in the Garand .

 

[M. De Land]

I made two errors in this post, the alloy Green Mtn uses (not Green River) is 1137 not 1134 which I keep flubbing for some reason. The first digit means carbon steel, the second digit mean carbon is the chief alloying agent and the last two digits are the percent in hundreds of carbon used in the alloy (.37 ) not 37 percent. This is one of the few companies that actually uses gun barrel certified steel and is the reason they are all I use. The barrels are also very uniformly bored, reamed and I think single point cut rifled, as I check them with a scope and plug gauges.

I just went over to Green Mtn. barrels web page and it says their muzzle loading barrels are "cut" rifled which almost certainly means they are broached as very few if any larger scale manufacture's single point cut rifle any more. I've acquired a single point rifling machine I hope to get running in the near future for my own personal curiosity . It needs some upgrades and I hope to work out a rack and pinion arrangement with a sine bar to do some gain twist experimentation.
I have never thought gain twist made much sense with bullets of groove diameter as the nose is always trying to out turn the base on the trip up bore but it makes a great deal of sense for paper patch bullets and perhaps patched balls. Metford of British fame discovered that gain twist worked very well with paper patched bullets of bore diameter ( instead of groove diameter) as it would unfailingly strip the patch the same at each shot which greatly enhanced long range accuracy.
I once got to watch some high speed photography in slow motion, of paper patch bullets leave a barrel muzzle and what I saw was that the high pressure gas that escaped the muzzle ,as the bullet base cleared, was what was breaking up the patch from the rear as the gas over took the bullet for a short way and began to break up the paper until the slip stream peeled it away. This was with even twist rifling. I expect the gain twist only enhanced this action. It was a surprise to me as I replayed it many times to verify what I was seeing.
I had previously supposed the rifling cut the patch and the slip stream did all the work but this was simply not what was happening. The high speed gas at muzzle exit was breaking up the patch from the rear, aided by the rifling cuts and the slip stream finished the job.
I once, for curiosity's sake, drove a paper patched bullet through a .45 cal barrel with modern .004 deep rifling. I used a two pound hammer , steel rod with tape covering to protect the lands from rod flex at each blow. The bullet bumped up nicely but the paper was not cut through at any point which surprised me. True , blows from a hammer are not the same as a trip up bore from a powder charge but non the less I would have thought the patch would be cut through.

 

[1BadDart]

In his book Walter M. Cline wrote that the best shooting target rifles (muzzleloaders) had soft barrels.

 

[M. De Land]

In his book Walter M. Cline wrote that the best shooting target rifles (muzzleloaders) had soft barrels.

Yes, I have that book as well. I was astonished that the steel or more likely wrought iron was so soft it could be finely shaved with a pocked knife. A barrel this soft would be dead to harmonics I'm thinking. It would also explain why they would shoot smooth after awhile and need to have the bore agitated before they would perk up again. I've read they really did pee down bore and let it set for awhile to rough them up although vinegar I would think would do the same job with a better smell.

 

[M. De Land]

There is a lot of very poor advice here on breaching and vent liners. First off the threads will not seal and there will be fouling back 3 threads or more if the breech plug does not seal against a shoulder. I also make my own vent liner and seat them against a shoulder as well. The hole into the bore is large enough to pass powder into the counter bore of the vent liner and that hole is right at the breech face but does not open the threads to the powder gases. The counter bored hole is tapped 12-32.View attachment 130798
Below is a plug final fit into a 50 cal smooth rifle barreL. The blue show its seated against the shoulder and is just touching the breech end of the barrel. I will machine the tang later.

View attachment 130799


If its not installed properly, and this was breeched by the barrel maker. You end up with foiling/solvent/oil traps like this. Isn’t this delightful? Grooving the breech face does about the same thing.

View attachment 130800

This is going In a 58 cal rifle. If you look close you can see the print of the grooves on the blue used to fit the plug. Yes it has a cupped breech. They give better velocity and cause no problems. Regardless of what people might think here.
View attachment 130801


Bore scope shows it looks like this installed. The vent is set into the cup so that the vent can be where it needs to be for the rifle design Without shortening the barrel. And yes this was done “back in the day”. The vent liner is also shouldered so all threads are sealed. The vent liner in this case must be removed before removing the breech plug. My 50 caliber heavy match rifle is done this way and is completely reliable and easy to clean IF the person knows how to clean a ML.
View attachment 130802

I agree about a shoulder flange on the liner if one has barrel wall enough to use it. I machined one for the nipple on the percussion gun with the 1 inch between flats barrel but the flint gun is only 13/16;s so I felt I needed the threads more than the shoulder. I timed the liner and cut the interior contour the same as the groove orbit diameter and coned the exterior of the vent instead of the interior. I don't care for interior coning as it vectors hot gas out ward. I made my vent of A-2 but did not harden it so I could easily drill it out when the time comes. A-2 has a lot of chrome in it so I expect it should have some longevity. Time and shooting will tell the tale.

 

[flintsteel]

A good tapered cotton pipe cleaner is also great for cleaning toucholes.

 

[M. De Land]

I agree about a shoulder flange on the liner if one has barrel wall enough to use it. I machined one for the nipple on the percussion gun with the 1 inch between flats barrel but the flint gun is only 13/16;s so I felt I needed the threads more than the shoulder. I timed the liner and cut the interior contour the same as the groove orbit diameter and coned the exterior of the vent instead of the interior. I don't care for interior coning as it vectors hot gas out ward. I made my vent of A-2 but did not harden it so I could easily drill it out when the time comes. A-2 has a lot of chrome in it so I expect it should have some longevity. Time and shooting will tell the tale.

I wonder if there is much if any difference in erosion resistance, to hardened alloy, as the same in the annealed state ?