Custom alloy for Heat Treatment

[mjgear]

Hi all, I am new to the forum and a part time caster who is starting to get serious about it. I am looking at getting into oven hardening of various projectiles in .30, .375 & .458 in conjunction with selective softening of noses etc.

All OK up to this point until I look at the humble wheel weight here (Australia). The alloy content is all over the shop and I have no hope of getting consistent results. Only one thing for it and that is to blend my own. This is where it get's a bit interesting, as I need a bit of help as to the best brew to use.

What I think I want/need would be 2.5% Tin, 3.0% Antimony, a trace of arsenic so I can harden and the balance lead. So if I use 1kg (2.2lb) Lino (4/11/85) + 3.0kg Lead + 120 grams (4.4oz) of 50/50 + 500grams (1.1lb) of High Antimony Shot (6%) this will give me a mix of:-

2.49% Tin,  3.03% Antimony, 0.1% Arsenic & the balance lead.

Is this going to work for oven hardening or should I be fiddling with the mix, bearing in mind that I want things tough not brittle and want to bring the noses back fairly soft in some applications.

Any feedback most gratefully received.

Regards

Michael G

[Kingfish]

Sounds like you've got it worked out pretty well. I've always heard to add a little magnum shot for the arsenic content for heat treating. My bag of magnum shot says 6% antimony also.

Bill

edit- Too much antimony will make your bullets brittle and lino has antimony in it too.

[JCherry]

mjgear,

How have you determined that your WW are no good? Have you tried to heat treat what you have available? It would be a shame to go to all of the trouble you are talking about without trying what you have.

I would suggest you go through the WW and separate out any with adhesive backing as they will be almost pure lead. Use those that have steel clips. Watch for any that may be zinc, I understand they will be very hard and will float in the melted ww. I have never encountered any zinc WW myself.

To heat treat I use a small toaster oven that has a glass front. When I started heat treating bullets I placed a thermometer inside and observed how much heat I was getting. Set the toaster to a setting where you get about 450-475  degrees Fahrenheit and put a couple of bullets in and let set for about 15 minutes, tap on the oven to see if any bullets slump. If they don't, work with the temp setting until you begin to see what setting they begin to slump at and then back the temp off about 15 degrees. It takes a bit of work but you need to establish the highest temp for that alloy. Once that is done back off the temp about 15 degrees so they don't slump and you can begin your heat treating of larger batches of bullets. I leave my bullets in the oven for an hour.

You want the highest temp without the bullets slumping. One trick I use is to place a small sheet of aluminum foil on top of the bullets to disipate the radiant heat from the upper heating elements to lessen the chance of hot spots.

I quench in a 5 gallon bucket of water which I place fairly close to the front of the toaster oven. I take my basket of bullets out of the oven and drop them as quickly as possible into the water bucket.  The faster you get the bullets into the water the better.  I normally let my bullets set in the bucket about 5 minutes, I see no reason for any longer.  

Give the bullets a full 24 hours and check for hardness. I have been using straight WW and getting hardness of 20 bhn is no trouble what-so-ever. Some alloys will go as hard as 30 plus but 20 has been great for me in full power 30-40 Krag loads (220gr bullet at 2000 fps.)

I have not heat treated any bullets larger than 8mm so what I have said above may not apply to the larger bullets but I think it will apply.

Casting with straight WW is better at around 800 Fahrenheit.

Have Fun, JCherry

[mjgear]

Bill & JCherry,
                       Many thanks for the tips and advice.

A friend has access to a commercial hardness tester that they use at his place of employ and we spent a day checking various types of wheel weights. All over the shop! We used pure lead, pure Linotype and a handful of moderately hard bullets as a control to cut out any "pilot error" on the tester. We did cull out the stick on's but even so we had about 8 BHN variance with no rhyme or reason to it between identical looking wheel weights.

I have not given up on the idea of wheel weights all together. I am stockpiling all I can get with a view to doing a bulk blending. If I process it in a 25kg (55lb) batches the "ying's & Yang's" may well balance out and give me something usable. (That will be a job for a miserable winters day).

Work has me pinned for the next week or so but I will get into it after that and see what I can achieve.

Regards

Michael G