Destruction of a boolit nose

[44man]

I made a mold for a semi-wadcutter boolit for my Ruger old Army last week. It shot pretty good. My friend dropped off his Pietta Remington with a 12" barrel so I could try it in his gun. I was shooting 32 gr's of Swiss FFFG. I found something that threw me out of kilter. I had one boolit move out from recoil and had to pull the cylinder to get it back in. I noticed the boolit had part of the nose eroded away from the cylinder gap blast. I started to keep track.
Boolit number one would be perfect of course but boolit no 6 and no. 2 had part of the nose gone. When no 6 came around where no. 5 was fired, the other side of the nose on no. 6 was gone too.
I was using a 30 to 1 alloy so I tried WW metal, water dropped. The erosion was exactly the same. I measured the gap after cleaning the gun and it is .010", not small enough to cause a hard jet of gas.
This has me wondering if some smokeless powders can do the same to our cast boolits. I have just never looked for it. I am going to from now on and wonder if all of you would also look because we all use different powders.
I took a file to a new boolit to show how they looked. 4 of them would have the flat one one side but no. 6 would have both sides cut.

[Bass Ackward]

44,

That's what's so neet about cast bullets. Just when you think you've seen most everything, something else enters the picture. As wild and varied of problems as I've seen, I never saw anything like that.

Even on short cylindered guns where I actually have loads that are flush with the face of the cylinder. I no longer have the strength in my hands to maintain grip the full way around the horn, so I have to re position my grip about the 4th shot. As a bad habbit I bring the gun in and do this where I look pretty much right at it while I adjust my hand.

I new a guy that went to the expense to have a tight B/C gap (.002) created and then he took a small file to the back end of his barrel to widen the gap in a horizontal position. He then had a few .000 gap on the sides while maintaining tight tolerances on the top and bottom. His theory was that the gas would follow the path of least resistance and flame cutting of the frame and of the cylinder pin area would be minimized. You would think that that would increase gas pressure on bullet on the one side. Actually both, but only one side would have a bullet in that position as the cylinder rotated.

What you will need to do is see what position this is happening, then you may have a clue. Good luck. Just make sure you report back.

[Bret4207]

The gap might be small, but it also probably isn't perfectly in line with the bore. Thats going to let gas escape even though you have a fairly tight B/C gap.

[44man]

I did study no. 6 boolit by pulling the cylinder again before shooting it. I wiped it off with a rag. Erosion was the same on both sides and each cut was exactly right angles to the forcing cone so my take is that the gap is even. It feels even putting the feeler gauge in from either side too.
The boolits were also seated about 1/16" below the face of the cylinder.
I blame the black powder and the quick initial blast against the portion of the nose sticking up. I have never seen it with a round ball and I have looked at a lot of them to see how much lube was blown out.
I get horrible accuracy with the Lee cap and ball boolit and will have to check and see if it is getting ruined too.
Next I will try putting a stiff BPCR lube in front of the boolits to see if it damps out some of the cutting.
My concern was if we can have it happen with smokeless with a powder like Lil'Gun with it's tremendous heat and cylinder blast.
Something else comes to mind too. The gap is large at .010". Would a tighter gap direct the pressure more sideways above the boolit instead of going into the front of the throats? It might just be the gun. It seems more likely a tight gap will protect the boolit nose. Blast direction control!
I know boolit jump does not effect accuracy and we all think the tighter gap is to increase velocity, but just maybe that is not the real reason to keep the gap small.
My Ruger shoots the boolit pretty good and the gap is .0065" but I never looked at the boolits as I shot. My next job.
Bass, makes me wonder what the guy that filed the back of the barrel actually did!

[44man]

I found the problem! The cylinder is too small in diameter, the chambers are too close and part of the barrel overhangs the next chamber providing a direct path for gas. The barrel from the inside edge of the forcing cone to the outside is only 3/64" and it looks like the rear of the barrel is overhanging almost that much.