Gas cutting picture

[JudgeBAC]

One of the CBA guys posted this picture and information regarding gas cutting, very interesting.

http://www.castbulletassoc.org/forum/view_topic.php?id=6874&forum_id=78

[runfiverun]

i wonder if there wasn't a void there to begin with and it was exploited.
that was extreme gas cutting right there.
it would also explain why the boolit stuck in the bbl.

[JeffinNZ]

George knows his stuff too. He gets good results in the shooting he does.

[theperfessor]

Not a member, can't view it.

[geargnasher]

Ditto.

Gear

[Shiloh]

Not a member, can't view it.


Ditto.

Gear

Same here.

Could someone copy and paste the photo?? I have only seen gas cutting on two revolvers. It'd be nice to see a photo.

Shiloh

[Bob Krack]

Here it is.....

[geargnasher]

Thanks, Bob.

That is extreme. I've recovered quite a few of my revolver boolits that had leaded the bore "chasing" the groove trailing edge, they all showed a narrow cut just twice as deep as the land engraving and about as wide as an index card down every land engrave on the boolit. The land engraves were clearly widened initially by slamming into the rifling too hard for the fairly soft alloy to handle. My hypothesis is that the boolit slightly "stripped" or "skidded" the rifling on initial engrave, opening up the land marks and creating gas leaks that trenched out the boolit the rest of the way down the barrel. A slower powder fixed it, but a harder boolit might have too.

Gear

[lwknight]

Geargnasher , you just made it occur to me that the way gas checks actually work is by blocking gasses that would pass when the twist rate would skid the rifling and cause a leak. The check can spin separately from the slug and not get skidded therefore maintaining the seal.

[BOOM BOOM]

HI,
Thanks for posting this.
Happy New Year All.

[JIMinPHX]

That's one reason why I shoot into a crumb rubber recovery trap, so that I can look for blemishes like that & troubleshoot my accuracy issues.

[runfiverun]

yeah george does rather well.
i hang out with his father in law.
we have been getting him into casting.

[44man]

Geargnasher , you just made it occur to me that the way gas checks actually work is by blocking gasses that would pass when the twist rate would skid the rifling and cause a leak. The check can spin separately from the slug and not get skidded therefore maintaining the seal.
Gear is 100% correct.
But I never found any indication of a check turning, they just stop the skid and maintain rifling size so gas has no channel. Checks appear to crimp to the boolit pretty tight once it starts into the rifling.
Make the boolit too soft and the check will also skid, causing leading. I have found boolits on the range with checks that skidded bad and they even had a wash of lead on them.

[Calamity Jake]

i wonder if there wasn't a void there to begin with and it was exploited.
that was extreme gas cutting right there.
it would also explain why the boolit stuck in the bbl.

I agree, that boolit had a void to start with, possibly hidden just under the surface.

[Char-Gar]

I note, with interest, that is a bevel base bullet.

[Down South]

That's one reason why I shoot into a crumb rubber recovery trap, so that I can look for blemishes like that & troubleshoot my accuracy issues.

I gotta build one of those traps. If nothing else, I could recover more of my lead.

I would like to see a before pic of those boolits. That huge bevel on the base could contribute to gas cutting.

[Shiloh]

I misinterpreted. I was looking for gas cut, flame cut revolver cylinders from hot .38 specials in a .357 mag.

Shiloh

[obssd1958]

I asked this same question on the original thread, but is it possible that the trough cut by the hot gasses was caused by, or made larger by, the fact that the boolit stopped in the barrel??


:?:

[JIMinPHX]

I gotta build one of those traps. If nothing else, I could recover more of my lead.

The box traps work real well. As long as you hit your target, you get pretty much 100% material recovery in an easy to handle form.

My most successful trap design is shown in posts #72 & 73 here - http://castboolits.gunloads.com/showthread.php?t=26627&page=4

Post #108 on page 6 gives you the general rundown with penetration depths of various boolits tested.

Post 378 on page 19 & post 397 on page 20 show the least expensive version that worked well. It was basically a plastic 5-gallon bucket full of crumb rubber with a steel disk in the bottom. If you wanted to use this with real high power rifles, you could use 2 buckets of crumb rubber, one in front of the other & only put the steel disk in the bottom of the second bucket.

[Buckshot]

I asked this same question on the original thread, but is it possible that the trough cut by the hot gasses was caused by, or made larger by, the fact that the boolit stopped in the barrel??:?:

..............Very possibly. I wish I'd saved some of the Minie' boolits I'd picked up over time, (instead of melting them down) but that was long before I had a digital camera. Very illustrative. A 58 cal Minie' provides a large canvas for high pressure gas to artisticly carve it's searching fingers to the atmosphere upon :-) Amazing how the gas finds entry past the bottom groove, then carves a path in both directions around the Minie' in the lube groove, then passes up through the next driveband 180º from it's initial entry point. Happens only within the barrel and only for milliseconds, but it's sure neough to wreak accuracy for that shot.

..............Buckshot

[Bass Ackward]

Looks like one of my sorted plinker class slugs. Am I getting gas cutting right in the MOLD!!! :grin:

I say lube'er, load'er and try'er again!

[Down South]

The box traps work real well. As long as you hit your target, you get pretty much 100% material recovery in an easy to handle form.

My most successful trap design is shown in posts #72 & 73 here - http://castboolits.gunloads.com/showthread.php?t=26627&page=4

Post #108 on page 6 gives you the general rundown with penetration depths of various boolits tested.

Post 378 on page 19 & post 397 on page 20 show the least expensive version that worked well. It was basically a plastic 5-gallon bucket full of crumb rubber with a steel disk in the bottom. If you wanted to use this with real high power rifles, you could use 2 buckets of crumb rubber, one in front of the other & only put the steel disk in the bottom of the second bucket.
Thanks for the link Jim. I remember following that thread when it was active. I was thinking it was you that came up with the box trap idea.

[JIMinPHX]

Actually, 357Max came up with the idea before me, but I did do a little work to refine it & document it a little better.