Copper Tubing problem - Rick

[Donna]

Hello Rick,

Thank you for the Jacket. I’ve Looked at it quite closely, I have the ocular section of an old riflescope that I use as a magnifier it is about equal to a 7 power or more. I see two things first off. One is that the sidewall is 0.352 inch OD and as you go down to the base it flares out to 0.3585 inch OD. I think this is the result of a poorly mated internal punch and core-seating die. The other is that there are cracks in the heel part of the jacket suggesting that the copper tubing was not annealed or was not annealed enough to allow the copper to flow. Instead because of its hardness it was pushed and it formed cracks in the heel of the jacket. I take it your die set is from Dave Corbin? Have you talked with Dave about the problem you are having with this die set?

You have to be using hydraulics’ to get the little hole sealed in your base, I’m using the Walnut Hill press and I’m able to close it down to 0.040 inch.

Donna :wink:

[Rick Teal]

Donna:

Thanks for looking at this jacket for me.

I'm quite surprised that the base diameter is greater than the finished diameter of the bullet.  I guess my measuring instruments aren't sufficiently accurate to pick this up.  My caliper and michrometer each show the base diameters to be less than .358.  Perhaps this is a manufacturing fault, or the dies may have bulged under pressure.

As to the "cracks", I've been of the opinion that these were actually fold marks which hadn't filled during the end flattening process.  The original samples that Corbin sent me when they delivered my equipment, had these marks in the heel, and I had considered them to be something that wasn't avoidable.

As to the annealing process, I've heated to colours ranging from the recommended dull red, through bright red and an orangy red, and always got the same results with fold marks in the heel.

I've never contacted Corbin about this, since I really didn't think it was a problem - just a deficiency inherent in tubing jackets.  I'm actually much happier with Butch's jackets since the cost is very little more than my material cost for tubing, and it saves me the time and tedium of making tubing jackets.

In order to close the hole in the base, I've simply been following Dave instructions by making sure I have some "piping" when I end round, and then using the end flattening die (and core seating punch) in my Series II press.  I'd say the hole closes up over 50% of the time.  In general, I've found that I have to use much more pressure on my press handle and dies when jacket making than I do when actually swaging cores and bullets.

Rick

[Donna]

Rick,

Maybe it is not the initial temperature of the jacket but rather the length of time at which the jacket is held at that temperature. I have only made a small quantity of jackets before I switched to Richards press and I have not had a chance to get my jacket-making die set converted over yet. But when I was making my jackets I was not getting any cracking and I did not heat-treat them either. Not trying to brag, maybe it was dumb luck.

Sorry, but I was not able to follow you about closing the end of the tubing jacket. Could you try to clarify it for me, because Dave never said anything about it to me? Thank you.

Donna :wink:

[Donna]

Never mind about the clarification, I reread your post and it dawned on me what you were talking about. I guess I need a little more piping.

Also those cracks at the heel of the jacket will not affect the external ballistics of the finished bullet, terminal ballistics maybe a different matter. But as long as you’re happy with Butch's jackets that’s all that counts.

Donna