antimony ... bar or magnum shot ?

So far it has been great with everyone's in put that I have received in these forums as far as my gearing up for my .308 ........
next question ....
have been advised to go ahead and mix in a bit of antimony with my ww to be ahead of the game as to hardening the boollits therefore bypassing the water drop or heat treat techniques ..... if so . , what would be more efficient , one pound bar , 30% antimony/70%lead or a bag of magnum shot to deal with ?
The bar I can get from Rotometals ... the magnum shot locally .
any how thought I would pick some of the immense amount of Knowledge here in this group of individuals ....thanks
digger

You know the composition of the Rotometals bar; you don't know the composition of the magnum shot (at least, not precisely). Further, the 30% antimony bar most likely contains several times the antimony content of the magnum shot, meaning you can use less of it.

It would depend on a few factors: your cost for the shot, your desired alloy, and the actual composition of the WW alloy.

To make a comparison, I will need to make a few assumptions. Let's say that your WW alloy is 0.5% tin, 2% antimony and Magnum shot is 6% antimony (I will also assume that reclaimed shot is similar). I'm not sure what alloy you're are trying to make, but I will use 4% antimony as the goal. For costs, I'll use $1/lb for WW, $4.29/lb for Superhard, and $1.80/lb for shot (rotometals reclaimed price).

For the superhard mix,
1 lb superhard + 13 lbs WW = alloy with 0.46% tin, 4% antimony.
The cost is $1.24/lb

For the reclaimed shot mix,
7 lbs shot + 7 lbs WW = alloy with 0.25% tin, 4% antimony.
The cost is $1.40/lb

Since you use less of the superhard, it is actually cheaper to go that way in this example. If there is any tin in the WW mix, you retain nearly all of it instead of cutting it in half. Of course, if these are not the numbers you want everything could be much different.

I can get reclaimed shot for $1.12/lb, so that would make the second mix only $1.06/lb. If you can get me some more specific information, I'll run the numbers again.

many of the bags of shot are marked 5%sb or 6%sb.
i'd look for them, then you know the antimony content.
you will however have more arsenic in the shot to deal with [good and bad], and the graphite coating you'll have to clean out of the alloy.

Wow ! .. excellent response , thank you ... the library of knowledge here is amazing !
Have no idea of content of my ww's so that part is a guessing game , have a few pounds of radiator shop solder.
With looking at the super hard bar on Rotometals , they nicely link over to the Lasc website and it's ratio's to play with .
theirs is a ratio of 16 lbs of ww to one of the super hard bars ... and comes up with 12 to 15 bhn , give or take the tin input.
Now will that hardness ratio be suitable for rifle ?
This formula is in the same ball park as bumpo628 proposes ....and it goes along with the recommended thought that one knows the amount/ratio to begin with compared to using shot .....all tho the arsenic contributes to hardness also ?

by the way , I like runfiverun's logo at the bottom .... "it's all an educated guess , till the trigger is pulled !"

And looking back at bumpo628's ratio of 13 lbs of ww to one lb of the super hard ... does the hardness increase even more with that over the 16 to one ? .... :coffee:

Digger, yes, that alloy will be fine for your 308. I use air cooled clip-on WW + 2% Sn (@ 12 BHN) in my 308 to 1900 fps. Haven't tried for higher velocities simply because I didn't need it and it shoots very well with zero leading.

The more over the 4% Sb you go the more brittle you will be making your alloy so the intended purpose would come into play. Yes, the more Sb the harder the alloy but again . . . the more brittle.

The arsenic role is primarily as an aid in quenching or heat treating. In this role 1/4% or 1% would make little difference. Yes, arsenic in itself will add to the hardness of the alloy but in the percentages we are talking about it wouldn't be much.

Rick

Antimony can be found in fairly high percentages in monotype. The one thing about monotype is, it is not generally melted and re-used. The letters are made - hard - then used as is and not remelted. Mono is one good way to add hardness. But be careful - a little goes a long way. It also contains quite a bit of tin. All this - IF you need that much hardness. I like to make WW material out of my pure(r) lead. enjoy Mike

arsenic acts as a grain refiner in the alloy.
it also creates surface tension,this is why they add it to shot.
the surface tension is what makes the shot round, too much of it will also create the same condition in your cast boolits [rounded corners].
keeping it around .25% is desirable, less still has benefits.

will probably order up some of Roto's super hard ....meanwhile will clean up and cast some 311299's air cooled to try out , ... start the learning curve .... the mold just came in the mail.

I can tell you from experience that the Superhard is very easy to use. I mark on the bar with a Sharpie how much I want to add to the pot then hold it in the melt at the mark until melted off. Very easy.

I'm a fan of Linotype and Monotype. If you can afford some SuperHard you can't go wrong with it either.

I agree with the post above. If you use magnum shot your guessing and the Arsenic content will be working against you! No more than .25% Arsenic, I doubt that you can get your Antimony up enough without exceeding that point.

SuperHard, Linotype or Monotype is your best bet. I am not a fan of water dropping for hardness. I consider it a myth and have doubts that it really works. But, it is also too much work if you do it right. (cast, size, heat and quench!)

Drop them, then size them and the are gonna soften. I think they soften in the barrel too, even though the experts say no.

I'd rather have an alloy that is hard to start because of Antimony and Tin. I use Lyman #2 for all of my rifle bullets. It hasn't failed me yet!

reclaim shot . would be hard to tell as it is a mix from many years of different brands .