Hardness issues

[Jeffjmr]

I use magnum shot primarily as my alloy. As is it consistently measures 14.3 BHN with my Lee hardness tester. I am less concerned with the accuracy of the 14.3 as I am with my inability to improve on it. Pure lead measures under 8 so I think I am in the ball park.

Water dropped measures 14.3.

Heated in convection oven at 425 degrees for one hour then water dropped measures at 14.3.

Magnum shot is supposed to have a fair amount of antimony and a bit of arsenic, which I read are essential to heat treating.

Pure linotype measures at 19-20. So I know the tester is able to differentiate.

What am I doing wrong that I can’t get my boolits any harder?

Jeff

[brewer12345]

Uh, what are you using it for? Why do you need alloy harder than 14?

[bangerjim]

Yea.......what the heck are you doing that needs that ridiculous hardness??!?!?!?!?!?

I cast 9-12 for 95% of what I shoot (and that’s a lot!) + PC. Never any problems. Easy to make. Perfect shooting. No leading.

Mabe ~14 for rifles slugs at the most.

Bangerjim

[Jeffjmr]

Just trying to follow what I read here, in the Lee and Lyman books as well as Fryxell’s articles.

They all say 14 BHN is good to about 20000 psi loads. That covers my Trapdoor and 71/84 needs quite well, though I am getting just a bit of leading in the first few inches of my 71/84 that has a pristine mirror bore.

But I am migrating away from jacketed bullets to cast in my 7mm and 8mm Mausers and those will be pushed to 30000 to 40000 psi.

Am I misinterpreting something I have read that says I need 20-25 BHN boolits for those kinds of loads?

Either way, my original point is I am not getting the expected results from published hardening processes and I am trying to learn why I might be experiencing difficulty.

Thanks,
Jeff

[bangerjim]

You will need some exotic and rather expensive alloys to get to 25. Personally I ignore that ancient "hardness required" thinking and go with the newer thinking that softer is better. And FIT IS KING. (And PC everything!) Those 2 rules give me perfect boolits with no leading, no smoke, no grease at all in all my many cals.

If you know the exact % makeup of your alloys (not just "pewter"), you can be pretty confident in the % and hardness results if you use the FREE alloy calculator on this site. I use it all the time with very good results against my NIST tester and CabineTester.

I know the EXACT makeup of all the alloys I have since I do not/will not buy them without an X-ray gun shoot from the yard I buy them from.

Good luck in your quest for the ultimate hardness you are seeking.

bangerjim

[Dusty Bannister]

I do not use the Lee hardness tester, but I do use the Cabin Tree/Cornaggia as well as the LBT test tool. I guess the first question is how long do you let your samples age after casting? Your reading should have shown that the percentage of antimony in the alloy will also affect how quickly the hardness of your alloy will progress as it age hardens. Many have great success with the Lee unit, so I suspect there is some error in your method of testing, or perhaps not letting the castings age harden.

Is it possible that you are not moving the HT bullets immediately and fully into the quench after baking in the oven? Also the temperature of the oven might not be high enough. Just because a dial reads a number, does not really mean you are at that temp. I used a cheap toaster oven with the dial set by testing sample bullets and increasing the setting until I get bullet "slump" then reduce the setting a little to prevent slump and get max effect from the quench. One really does not need to do that for the majority of shooting needs.

If you are getting a little leading in the first few inches of the barrel in the rifle, you might see if a slightly larger bullet diameter will help. It might also be that you are not conditioning the barrel before you shoot and starting with a squeeky clean barrel. A very light application of bullet lube on a dry patch passed back and forth through the barrel prior to the first shot might resolve that issue. Not enough lube to smear lube on the surface, but just enough to leave a slight residue. Dusty

[popper]

Drop in ice water and check in a week.

[TaylorS]

The way I read it the way to go is to GC loads over 20k psi not necessarily make the boolit out of cobalt. GC pushes the soft lead to fill the bore without gas cutting and leading caused from a plain based boolit. Keep in mind I’m still messing with light pistol stuff have not dived into rifle casting yet. But trap doors and black powder cartridges were designed around a BHN of 12 being very hard with most being much softer.


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[Jeffjmr]

Thanks all for the responses. I have some gas check molds and am not concerned about hardness with those. But I do have some plain base that from what I read and from some posts here, might benefit from something a bit harder than 14.

I did not wait to test. I tested air cooled, water dropped and heat treated all poured from the same alloy, each as soon as they were room temperature. I was looking for proof and to measure that the extra steps, water dropping and heat treating, had a benefit. I am confident that my testing process is good, as I get repeatable results with my several different alloys with my tester.

But am I mistaken to expect an immediate difference? Does the heat treating and water dropping affect the hardness AFTER aging? Seems counterintuitive but if that is the rule, I’ll be patient and test again later.

As for PC, I am intrigued and continue to study about it. I must admit I’d feel better about it if someone could provide some scientific data on the long term effects on bore erosion versus cast and jacketed. Anecdotal evidence like “I have been shooting PC boolits for many years and thousands of rounds and I see no wear to my bore” is not enough to convince me given most of my shooting involves antiques and C&R pieces. I got into casting specifically to minimize wear and tear on my collectibles.

Jeff

[jsizemore]

Test in a day, in 2 days, test in a week and again in 2 weeks. You will be amazed. I size and lube them the day they're cast to reduce the stress on the lubesizer.

[Jeffjmr]

Test in a day, in 2 days, test in a week and again in 2 weeks. You will be amazed. I size and lube them the day they're cast to reduce the stressp on the lubesizer.

Dang!

Tested today at a whopping 27.2! No apparent difference between water dropped and air dried but the heat treat sure made a difference!