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Does .38 Ammo wear down .357 Chamber?


Aunt Jen

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I've asked this before, elsewhere, but I'm going to ask again because I still don't get it.

 

I understand that it's okay if a .38 is fired in a .357. In fact, it's common, and cheaper. I'm not worried about it. It also makes the gun more versatile.

 

But it is still my curious nature to wonder how that works.

 

It seems that if the .38 is fired, that the bullet will obturate, beginning when fired. That the bullet will somewhat flatten and spread to fill its surroundings, which will help it engage the rifling. But when it's still in the chamber, it will likely expand some before it gets to the barrel. The .38 is shorter than the .357, and so the obturation may be produced before it gets to the barrel. Either that, or it's flying in free space before it gets there.

 

In either case, this makes me wonder if it will hit on or wear the beginning of the barrel.

 

I am not worried about wearing out the gun. I'm just the curious type who wonders how the mechanism works.

 

Thank you

 

Aunt Jen

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Howdy

 

Very good question.

 

Take the cylinder out of one of your revolvers and peek down into a chamber from the back side. You will see the majority of the chamber is one diameter, but the very front portion is a little bit smaller in diameter. You will see a very short shoulder separating the two. The front, narrower portion of the chamber is called the chamber throat. Ideally, it is sized the exact same size as your bullets, or just a couple of thousandths larger. The rear, larger diameter of the chamber houses the shell, which of necessity is of a larger diameter than the throat, because the shell is larger in diameter. At the rear of your barrel is a funnel shaped cut called the forcing cone. Then finally, there is the rifling.

 

With a 357 Magnum chamber, the shell of a Magnum round will completely fill up the entire length of its portion of the chamber. The bullet will sit nicely in the chamber throat. When the round is fired, the bullet traverses the chamber throat before exiting the cylinder. With a properly sized bullet in a properly sized chamber throat, the bullet will be prevented from distorting in shape because the chamber throat completely surrounds it. When the bullet exits the cylinder, it enters the forcing cone. The purpose of the forcing cone is to funnel the bullet properly into the rifling, just in case there is any misalignment between the cylinder and the barrel.

 

It is the nature of modern progressive powders that pressure builds as the bullet continues down the barrel. Pressure is not very high as the bullet exits the shell.

 

A 38 Special round is only about 1/10" shorter than a 357 Mag. So when the round is fired, the bullet does have to jump about 1/10" before it reaches the chamber throat. But pressure has not built up high enough at that point to distort the bullet, it will enter the chamber throat nicely and be directed on its way just like a Magnum bullet. The chamber throat will 'cradle' it and send it to the forcing cone without any distortion.

 

There is the carbon ring that tends to build up at the mouth of a 38 cartridge in a 357 chamber, but that is a different story.

 

There is also theoretically a slight loss of accuracy as the bullet transverses that 1/10", but it is so minor it cannot be readily measured.

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To add to Driftwood's characteristically great info, I shoot very short .45s, on the order of 3/8" shorter than the LONG Colt for which the guns are chambered. I notice NO significant loss of accuracy (with careful load development, I have shot one-hole groups using the short cases), and though you will get a build-up of carbon ahead of the short cases, this is readily removed with a a tornado brush and Hoppes, and there is absolutely ZERO negative effects on the chamber itself, other than this crud ring. After many tens of thousands of short cased loads fired through my guns, when cleaned, the chambers are absolutely no different than they started. AAMOF, it is my considered opinion that using the light loads we ALL used (no cowboy round is what anybody would call "hot" ), I don't think it is possible to wear out a chamber or barrel EVER. I think very like some of the old .22 caliber "shooting gallery" guns of the middle part of the last century, even millions of rounds didn't seem to hurt them.

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Yup.

The bullet only obturates when it is pressed firmly into the forcing cone and barrel.

 

As stated above, there is not enough pressure to start that process until the bullet meets significant resistance. So the bullet does not swell any real amount until it gets "caught" between the pressure of the gases behind it and the resistance of the forcing cone, then barrel.

 

Does this and the info above help?

 

Lead bullets are relative soft and slick, so they cause very little wear. The wear comes from the hot gasses that may slip around a bullet and the harder jacketed bullets going down the bore. But for lower pressure pistols, there isn't enough velocity to wear like a high speed rifle can wear. Some say that the most wear our guns get is from cleaning them. :D

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The same situation can occur in any "dual chambered" gun be it 44mag/44spec, 357/38spec, 22lr/22short, etc. As long as the "carbon ring" is cleaned out as a part of routine cleaning everything should be OK. I had a buddy that had a revolver in the 22lr/22short department and had been shooting gobs of 22 short out of it. So much so that he really had forgotten how much he had actually shot out of it (and was real bad at cleaning his weapons). We went out shooting and he then tried to chamber some 22lr rounds in the gun and could not at all. The carbon build up was too great for the rounds to fully chamber. (this can happen with any of the above mentioned caliber combinations). A thorough cleaning finally allowed the chambering of 22lr, however upon close examination of the chambers there was a ring actually cut into the chambers just ahead of the shorts case mouth. This happened from a prolonged combination of lack of care/cleaning and use of the shorter cartridge. Smithy.

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Interesting question Jen, thanks for asking it.

 

The only negative I've seen is when someone shoots 38s for years and then switches to the longer 357s. A pard on my posse did this one time and his rifle had trouble chambering the longer rounds. IIRC a good cleaning solved the problem, but he borrowed some 38s for his rifle to finish out that match.

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Interesting question Jen, thanks for asking it.

 

The only negative I've seen is when someone shoots 38s for years and then switches to the longer 357s. A pard on my posse did this one time and his rifle had trouble chambering the longer rounds. IIRC a good cleaning solved the problem, but he borrowed some 38s for his rifle to finish out that match.

 

 

Dave, Ive done it. After thousands of short rounds, I had to kinda push hard to get the Ruger to swallow "LONG Colt" rounds, but honestly, at Cowboy ammo levels, if it chambers and the gun turns, yer good to go. Now before shooting "Ruger Only" level loads, yeah buddy, clean that rascal good.....

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It was his rifle that had problems.

 

My pistols won't chamber self defense 357s, but it's a leading issue, need to get the lead out.

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Howdy,

I once bought a 357 revolver that had a ringocrud in the chambers.

I put a real cleaning on it and started shootin 357.

After 3 cylinders full I could hardly get the emptys out.

More cleaning with the same results.

The dealer took the gun back as there were pits in the metal

where the ringocrud had collected moisture and rusted into the chambers.

 

A little lesson, deal with a reputable dealer.

Best

CR

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Dave, Buy yourself a Lew's Lead remover and clean them revolvers good and that problem will go away. I saw many a 357 revolver used to fire 38 spl wadcutters in PPC and other police matches. Some of these guns were used to fire many thousands of rounds,more than SASS guns and were well cleaned. They would fire 357 ammo anytime it was used.

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