Heat hardening CB base

[popper]

Anyone try to heat harden the base of a CB as a GC replacement? BHN of copper is ~ 30, Pb alloy can get to >25 with arsenic or sulfur added. Seams like a 30 cal base heated on a hot plate for 10 sec. should get .25" up to temp and then quench to get a hard base. PB CB could then be as hard as a GC and a softer nose.

[williamwaco]

Very interesting.

Try it out and let us know.

I don't think it will work on a gas check bullet but It woulod be interesting to try on a plain base design.


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[mooman76]

Someone here had a method of making a soft nosed cast boolit. I think there may be a sticky on it but I don't think you can just heat the base a treat it but it's worth a shot.

[popper]

I'm casting PB 30-30 and intend to try it. I know I won't get real GC performance but maybe close. Not trying for soft points, but thought if a moderate hard CB w/GC takes higher fps, I could harden the base and partially up the bullet to allow higher fps.

[DLCTEX]

Check out Bruce B's two part casting for softnose hunting boolits. It's a sticky. I think it will be easier than what you're trying to do.

[375RUGER]

maybe try heating them up to 400*F or so, hold for 1 hr and then water quench the base only.
I don't think 10sec on a hot plate is going to do anything for you. The lead is going to soak up that heat fast.

[Chamfered]

Seems like it would be more work than just checking it, assuming you had the GC mold.
How do you plan to heat them? It seems like the thermal transfer on lead would make it hard to heat just the base.
How about water quenching them straight out of the mold and then try to "anneal" the noses by heating them back up and then letting them air cool.
I know I have read about similar duplex castings before, I will have to look thru my books to see if I can find the article.
Good Casting.

[runfiverun]

i'd just water drop them.
you are still gonna be limited in velocity with the plain base.
i would almost bet money a filler would increase your velocity window more than a heat treating will alone.

[waksupi]

Amazing, what a person can dig out of the stickies if they look around.

[longbow]

I think you are kinda low on BHN for copper. Pure soft cast copper may be as low as 30 but rolled copper sheet runs more like 60 to over 100 BHN.

Also, to heat treat properly, you have to get lead alloy to just below the melting point (450 - 475 degrees F) for a few minutes before quenching to achieve good hardness.

Even if you can get a harder base, I doubt you will realize any useful velocity gain because it is still a PB boolit.

However, nothing ventured, nothing gained and no harm in trying it. Let us know how it works out.

Longbow

[popper]

My theory is that a gain rifling actually reduces the rotational stress on the CB, reducing deformation. Think of a brass screw in a piece of hardwood, the screw breaks where it enters the wood, 90% of the time. My thought is that a soft front band will slip, rear band will grab and the hard rear section would obturate the mid section. Heated the base of several last nite on a temp controlled (420) hot plate and WD. Actually took 30 sec to get the nose to 220F. I'll load em later this next week and hopefully make a comparison shooting. You don't get twisting of J-B, I think PP might be doing the same thing as well as artillery shells that use a slipping drive band.