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.357 Mag question
Fatstrat
Member Posts: 9,147
I saw a post on a forum that said firing lighter weight .357 Mag ammo (125GR) in a S&W Model 66 would cause it to shoot loose faster than heavier (158gr) ammo. Apparently due to the lighter weight design of the gun. Is this true? And if so, why?
Comments
http://www.gunblast.com/Butch_MagnumLoads.htm
Lighter bullets can use more powder to propel them. Heavier bullets use less powder to propel them because the bullet has more weight against the pressure building up in the barrel from the gases.
I guess what I'm saying is if you load 125gr bullets w/ Win 296 to max power your going to get a LOT of wear & tear. You load a 158gr bullet to max power with Titegroup the gun will last longer. The gun isn't going to fall apart in your hand but you will find the crane holding the cylinder will become sloppy as other things.
Any .357mag will wear & tear more when you load hot loads all the time.
Lighter bullets can use more powder to propel them. Heavier bullets use less powder to propel them because the bullet has more weight against the pressure building up in the barrel from the gases.
I guess what I'm saying is if you load 125gr bullets w/ Win 296 to max power your going to get a LOT of wear & tear. You load a 158gr bullet to max power with Titegroup the gun will last longer. The gun isn't going to fall apart in your hand but you will find the crane holding the cylinder will become sloppy as other things.
That is what I was looking for.
Best
Interesting article. I agree with his conclusions that the most important factor was bullet length, not weight or pressures, although they DO have some effect. Reducing the distance of free flight the bullet makes from the cartridge until it seals the barrel by engaging the rifling does appear to be the strongest factor in wear and tear on these revolvers. If you use a bullet that is long enough to seal the throat just as or even just before it leaves the brass case, it eliminates the hot gas blowby into the barrel and the peening of the six oclock position of the throat by the free flying bullet. I hadn't considered this explanation before. Many thanks to the author and to m1aguy for providing the hotlink. [:)]
Well, you can't truly seal the barrel throat before the bullet starts to leave the cartridge case, because if you did, the cylinder wouldn't turn or open!
But yes, my understanding is that the combination of increased gas blow-by past the shorter 125 grain bullets, and mostly just overall higher velocity when they smack the forcing cone is what's the biggest "killer" of these K-frame .357s.
All .357s will get some topstrap erosion from plasma "flame cutting" from .357 rounds. But the K frames (models 19 and 66) in particular are particularly susceptible to cracking of the barrel forcing cone. Lots of really hot rounds can also knock them out of time and/or create endshake (front-back looseness) of the cylinder.
Basically, they're meant to shoot mostly .38s and not so many .357s. If do that, and try to stick with 158 grainers (rather than 125s) these can still last for a long long time.
If you want to fire a lot of full power .357s for whatever reason, you're better off with one of the L-frames or maybe a gun from a different maker.
On the J-frames, I'm not really sure they're any tougher (especially around the forcing cones), but as a matter of practice, virtually nobody is masochistic enough to try and fire thousands of full power .357s through these the way people do with more traditional "service" sized guns!
Emmett
I can't believe that a 357 mag was "not rated" for +P38 special. If the +P 38 tied your revolver up, there was some other factor.