Heat Treating

[onesonek]

I was reading on LASC about heat treating,,,, a question of curiosity I have for those that may have done it.
Will a heat treatable boolit alloy have any gain in BHN with an oven temp below 400 degrees?

[cbrick]

onesonek, as you can see in the chart I did test at 400 degrees but not under that temp. At 400 CWW + 3% Sn (that started out with air cooled bullets at 11-12 BHN) went to 15 BHN in two weeks.

If you try it under 400 and your CWW alloy is already 11-12, yes, it should HT but I don't know if you'll gain enough to make it worth the effort.

The percentage of both Sb and Sn in your alloy will also play a part in how much, how little and how fast or slow your oven HT will effect your alloy.

Minor changes in BHN had little effect in long range revolver group testing, large differences in BHN had a large effect on groups as did any BHN much over 18. Too much of a good thing is clearly not a good thing, at least in my testing.

Rick

[onesonek]

Ok Rick, well here's my goal,,,right wrong, or indifferent:wink:
I would like to use the same alloy for both pistol and rifle, and want no if any expansion with these wide meplats. So I'm hoping to get an air cooled alloy of around 14+ to run at 12-1300 fps. Then HT it to 18-19 for running in the rifle at 1600-1650.
It looks like at 400 degrees one gains about 5 points. That would work close I think, but should my alloy go 15, then I was hoping a lower oven temp of say 390-395 in hopes of a 3-4 point gain.
I suppose I could go with a lower BHN to start with then heat treat the two at different temps.
Here's what I have for alloy's on hand to play with
co-ww's from TheCaptain
iso comming from Muddy Creak Sam
And pick up some old Lino from a printer
I was kinda hoping I might blend them in a 1-1-1 fashion and maybe hit the BHN14, but guessing there, that could be altered easy enough
Just trying to keep it somewhat simple and not really meaning to lock myself into a trend of thought.

What would you do? I'm highly open to ideas and advice.

[cbrick]

I would like to use the same alloy for both pistol and rifle, and want no if any expansion with these wide meplats. So I'm hoping to get an air cooled alloy of around 14+ to run at 12-1300 fps. Then HT it to 18-19 for running in the rifle at 1600-1650.

What would you do? I'm highly open to ideas and advice.

I really see no need for HT'ing for what you describe. Air cooled CWW +2% Sn should work very well for your 1200 to 1300 fps handgun loads, 14 BHN really isn't needed. 1600 fps to 1650 fps in a rifle is well within a reasonable range for air cooled CWW. The catch here is that the bullets properly fit the firearm.

What I do for both of what you describe is use air cooled CWW. My 308 rifle shoots 180 gr bullets to 2,000 fps with air cooled CWW with very good accuracy and zero leading. Every single handgun that I load for uses air cooled CWW with the exception of very high end Freedom Arms revolver loads that I heat treat to 18 BHN and low end 45 ACP HP loads, these use a softer alloy, about 8 or 9 BHN.

Don't over think this and make extra work for yourself. Test the loads your thinking of and see how they work without HT'ing first.

And remember, bullet fit is extremely important, much more so than using a higher BHN alloy.

Rick

[Marlin Junky]

And remember, bullet fit is extremely important, much more so than using a higher BHN alloy.

Rick

Yep... air cooled clip-on WW metal will work well all the way to 2000 fps if your rifle/carbine barrel is up to it and the boolits fit properly.

I feel I need to qualify "air cooled clip-on WW metal" though. When I cast near 800F, while using the heavier ferrous molds in .30-.35 caliber, and let my boolits cast of clip-on WW metal age for a few weeks, they'll register BHN 12-13 when tested with my Lee hardness tester. In other words, casting conditions and aging can have an effect on the hardness of your boolits cast of WW metal.

MJ

[sqlbullet]

I have heat treated that isotope lead as hard as 32. I think you will find casting isotope lead from a 675° pot, water dropping from the mold, then post heat them to 400° for one hour and quench again will get you pretty close to 18-20.

Here is a link to the test results (http://www.fellingfamily.net/isolead/) my son came up with when he used this lead for his science fair project.

[onesonek]

THanks for the input guys!!