Range lead: add antimony (Rotometal super hard alloy)

[357shooter]

OK, so it turns out the range lead that I have (about 60 lbs left) hardens kinda slow. I only have some water dropped bullets left, after 10 days they are way up to 21BHN. I triple checked using multiple bullets to make sure.

All my air cooled from have already been shot at the range, so I can't check their hardness... I'm guessing they would be 14 or 15. (not an educated guess, just a guess)

Today 5 lbs of Rotometal superhard alloy arrived. it's 30% antimony. Which I ordered before seeing the 21BHN, and estimated the current batch at 14-15.

This is for 357 magnum, midrange loads and some 2400 magnum loads & target shooting. No hunting. I was thinking that 14-16 BHN is just about right. When the WD bullets were at about 15 they shot absolutely great. 21 isn't bad but not as good as the 15.

If I add some of the antimony via the Roto-alloy will the hardness of the air cooled bullets increase a bunch, or will they just hardnen a bit quicker? Or should I just hang onto the suerhard-lead for sometime in the future?

Hoping to lean from y'alls advice as I appreciate the input and help you guys give.

Add some anitmony or not?

[Edubya]

I don't claim to be the most knowledgeable on this subject but there are some great stats and information on http://www.lasc.us/FryxellExpansionOfCastHP.htm . If you go about half way down on that page, you will read about good shooting boolits at BHN of 8-14 at 12-1400 fps. The old timers didn't have all of this fancy alloy to mix in with their resources and they paved the road for us. We ought to value their words.
EW

[melloairman]

It is not a answer to your question . But it might help you in the future . I have done some heat treating in the oven . If you play with the temp and the time you might be able to work it out . There is a chart at the end of the article that has some good info . By the way my range lead when oven treated responses slowly to the treatment as well . And I have used a reglar oven with good results Marvin
http://www.lasc.us/HeatTreat.htm

[Edubya]

Here you go, this is the site that I was looking for: http://www.lasc.us/CastBulletAlloy.htm
EW

[454PB]

I would be surprised if air cooled range lead tested that hard. Most clip-on wheelweight metal is around 10 to 12 BHN when air cooled. My water dropped WW boolits test around 26 to 28 BHN after a month of aging.

I use air cooled WW boolits in .357 magnum at up to 1300 fps. with no leading if they fit right.

Yes, adding the high antimony alloy will increase the hardness, but I don't think you need additional hardness. I'd save it for alloying with pure lead and 1% to 2% tin for a harder mix.

[357shooter]

Thanks for the LASC links, it's one of my favorites. I'm very familiar with it.

So I already know my gun likes my target loads at 15BHN better than anything else. Better than 12 or 13 and better than 19 or 20. Works well with 2400 and also 700X, which I have in stock and tend to use a lot of.

It's good to now know that adding anitmony increases the hardness of air cooled bullets. I'll probably save the super-hard for some other time. Thanks


Updated: it's kinda good to hear that someong else (454PB) also gets a large increase in hardness with waterdropping.

[cbrick]

If I add some of the antimony via the Roto-alloy will the hardness of the air cooled bullets increase a bunch, or will they just hardnen a bit quicker? Or should I just hang onto the suerhard-lead for sometime in the future?

Sure adding antimony will harden air cooled alloy and the higher the percentage the harder they will be right up to pure antimony. Use common sense though, antimony is an extremely brittle metal and the higher the percentage the more brittle they become so your intended target (such as steel targets) should come into the equation.

Also if heat treating or quenching, a 2% alloy will have a longer hardening time curve than 4%. The higher percentage of antimony reduces the time needed to achieve final hardness.

If you decide to use your Roto super hard keep your antimony at 3% max, your 14-15 BHN will be very easy to achieve without quenching and 2% could well do it for you, plus your super hard will last much longer. Quenching a 3+% antimony alloy could (should) well put you over your 15 BHN goal.

Assume your range lead has no antimony (it will have some depending on the type of shooting done at the range) and you add all 5 pounds of the super hard to your 60 pounds of range lead you will have a 2.4% antimony alloy (plus what was already in the range lead).

Converting to grains your range lead
= 420,000 grains
5 pounds super hard
=35,000 grains @ 24,500 grains lead and 10,500 grains antimony.

Add the 420,000 grains to to the 24,500 = 444,500 grains lead and 10,500 grains of antimony or 2.4%

Hope this helps,

Rick

[357shooter]

Sure adding antimony will harden air cooled alloy and the higher the percentage the harder they will be right up to pure antimony. Use common sense though, antimony is an extremely brittle metal and the higher the percentage the more brittle they become so your intended target (such as steel targets) should come into the equation.

Also if heat treating or quenching, a 2% alloy will have a longer hardening time curve than 4%. The higher percentage of antimony reduces the time needed to achieve final hardness.

If you decide to use your Roto super hard keep your antimony at 3% max, your 14-15 BHN will be very easy to achieve without quenching and 2% could well do it for you, plus your super hard will last much longer. Quenching a 3+% antimony alloy could (should) well put you over your 15 BHN goal.

Assume your range lead has no antimony (it will have some depending on the type of shooting done at the range) and you add all 5 pounds of the super hard to your 60 pounds of range lead you will have a 2.4% antimony alloy (plus what was already in the range lead).

Converting to grains your range lead
= 420,000 grains
5 pounds super hard
=35,000 grains @ 24,500 grains lead and 10,500 grains antimony.

Add the 420,000 grains to to the 24,500 = 444,500 grains lead and 10,500 grains of antimony or 2.4%

Hope this helps,

RickThanks, that's extremely helpful. Great info!

[imashooter2]

I've been using range scrap collected over a period of 8 to 10 years from a couple of different indoor ranges. It runs between 12 and 14 BHN air cooled and water drops 18 - 22. This from a dozen samples pulled from buckets all across the time line.

I've shot a lot of this scrap air cooled through .357 mag revolvers and carbines using 2400 just as you plan to. It works fine as is with no additions whatsoever.

I've never seen a need, but if you have a hankerin' to experiment...

Your existing alloy seems similar to what I've had. I would start with enough super hard to give 1% additional antimony tops and then cast a few to check hardness. Adding more is a lot easier than taking it out.