Possible dumb question

[splotch]

I understand that cast bullets with gas checks wear a barrel less than jacketed bullets. But why? the metal (which I assume is the same as jacketed materal) of the gas check runs the entire length of the barrel just like a jacketed bullet so shouldnt the wear be the same. Is it just the pressures are lower and less powder is used causing less wear? Let me know

[jcren]

Actually it is mostly the difference in bearing surface. For instance, I shoot a 230 grain 308 boolit with gas check. The check is only about 1/8 inch long, for approx .039 square inches of hard metal rubbing the barrel. If this bullet wass jacketed, it would have nearly an 1 1/4" bearing surface, or .385 square inches. Basically 10 times the wear.

[1johnlb]

Im more inclined to believe that hot gases wear out barrels more so than the actual projectile, unless your talking AP.

[georgerkahn]

I concur with 1johnlb. One of my major reasons for using gas checks is re bullet obturation -- but, that's a different area of discussion . Just a HUNCH, too -- I can't base this on fact -- at least in my case the ammunition I load and shoot with bare cast boolits is generally lower pressure/speed than their jacketed counterparts. I kind of think of the gas check as a "nail punch" which the ignited powder's gas squishes down to seal barrel and keep gasses from either going around the boolit, or, even through it. In this case, the lead is what's going down the barrel, with this tiny "pusher, sealing washer" behind it. Just an early Saturday morning thought...
BEST!
georgerkahn

[Hickok]

In a revolver, I think the major wear from jacketed bullets comes from the harder copper jacket slamming into the forcing cone, whereas the softer cast boolit doesn't abrade or remove metal in the forcing cone as much as the copper jacketed boolit. Even with a gas check, the cast boolit is easier on the throat, because the front of the boolit is soft, and it contacts the forcing cone first.

In rifles, I believe powder gasses are what contributes most to a worn out barrel, burning out the throat in front of the chamber after repeated rounds. Barrel wear from the harder and more abrasive copper jacket as compared to a softer "slicker" cast boolit is secondary to wearing out a barrel. Yes, I think a barrel would receive more wear from 10,000 jacketed bullets than the same number of cast boolits.
But I believe the throat would suffer the most wear and erosion from powder gasses.

[jcren]

With all due respect gentlemen, I would kindly point out that I can hold the 6,000 degree f flame of an oxy-acetylene torch to a piece of steel for a split second then touch it and there is very little warmth. In the same split second 1 hot load through my 30-06 will warm the barrel nicely, but powder only burns around 3,300 degrees f. Energy does not pass from a gas to a solid as efficiently as from one conductive solid to another. Must of the heat felt in the barrel is from the friction of the projectile. Lead itself can be used as a lube, plus we lube them more and poke em through the barrel slower. That is why barrels on lead spitters almost never "burn-out".

[Hickok]

This is going to be interesting and informative!

[tjones]

Jcren, you best think of a plasma cutting torch. High pressure and the plasma of gases quickly erode the throat. You just need to have worked on machine gun barrels. -tj

[jcren]

Excellent point, I wasn't thinking in terms of rapid fire. However, plasma is typically in the 40,000 plus temp range. I think under sustained fire, it becomes more a combination of factors as the hot barrel is more easily eroded.

[Minerat]

I use them for one reason. They are cheaper then J word bullets.

Added benefits are they help reduce/prevent leading, I can also push them closer to j word bullet speeds and still have the fun of casting.

[1johnlb]

I also think it's more a combination of bullet and gas, but the one thing that stumps me on the bullet is why would it wear out the muzzle. I tend to think that the gas erodes the throat from temp and repeated fire but the muzzle because of that sudden rush of hot gas and powder after the bullet leaves the muzzle.