Boolit Alloy Hardness

I was sittin' round wonderin' about bullet alloy hardness the other day. The question came to me, if 20 - 1 lead/tin alloy is BHN of 10 according to some info I had from Lyman, if you took WW alloy and made it the same BHN as the lead to tin alloy, would it expand like the 2 ingredient alloy or would the ww alloy still be a little less ductile than the lead/tin alloy, considering it has more "stuff" to make it not as ductile, in the mix of the ww alloy? Or is BHN 10, BHN 10, regardless of the mix used to get there?

Antimony makes the alloy more brittle.

Given the lower velocities of a revolver or muzzle loader, softer lead seems to stay together better. It can flatten, mushroom, etc without breaking apart. Increasing antimony will make a boolit more and more brittle, the more added.
But at the lower hardness readings you really will not see any difference so if you could get WW metal that soft, it should act the same. You might need to add pure lead to WW metal to get that soft.
The question is always what gun, what velocity, etc. Within a certain velocity range of say a .41 mag and up, there is no need for any expansion at all as long as the boolit has a nice meplat, in fact it can ruin penetration for hunting if shot fast enough while a slower soft boolit will still go through a deer.
Then a smaller caliber needs expansion but expand too much and boolits can stop too quick, that is why a .357 is hard to balance for the game shot. There is not enough boolit weight for good penetration yet expansion is needed because of the small diameter.
Alloy and hardness can be strange. Take a .45 Colt and very hard boolits work great but use the same boolit in a high velocity gun and they do not kill well at all so expansion has to started but expand too fast and meat destruction goes way up. Make a boolit brittle and it can break apart.
I can see what you are asking and the answer would be that 10 BHN with any alloy should work so close to the same that you will never tell the difference.
The hard part is choosing the proper alloy for the purpose needed.
Pure lead or 20 to 1, 30 to 1 is fantastic with black powder, etc, even for the largest animals but just does not work in a .44 mag, etc. It has a lot to do with powder impulse and pressure rise with smokeless, you do not want boolit damage or slumping in a modern revolver or any gun for that matter.

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Originally Posted by giz189

I was sittin' round wonderin' about bullet alloy hardness the other day. The question came to me, if 20 - 1 lead/tin alloy is BHN of 10 according to some info I had from Lyman, if you took WW alloy and made it the same BHN as the lead to tin alloy, would it expand like the 2 ingredient alloy or would the ww alloy still be a little less ductile than the lead/tin alloy, considering it has more "stuff" to make it not as ductile, in the mix of the ww alloy? Or is BHN 10, BHN 10, regardless of the mix used to get there?

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The lead-tin alloy will be more ductile, even if the two different alloys have the same BHN.
But the WW alloy does not necessarily take a back seat to the 20-1, because in order to reach the (lower) 10 BHN with WW alloy you need to dilute it with lead, at which point the percentage of antimony is then lowered enough so as to have no significant impact concerning brittleness.

For most practical purposes, the loss of ductility that occurs with the introduction of antimony does not become significant until the percentage of antimony exceeds close to 4% or more, and even at that the introduction of additional tin seems to help counteract that effect.
This is why simple WW alloy at <4% Sb can be successfully used with cast hollowpoints, providing impact velocity and HP profile are optimal.
It also explains why Lyman No.2 (5/5/90) is slightly better (for purposes of bullet integrity) than harball alloy (2/6/92). Both of these alloys are noticeably higher in antimony than wheel weights, but the additional tin in the No.2 provides an advantage concerning ductility.
Yet I know plenty of individuals who successfully use the hardball alloy for hunting purposes with no dire consequences; therefore, the need for "ductility" can be subjective.

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Or is BHN 10, BHN 10, regardless of the mix used to get there?

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In answer to your question, yes, 10 BHN is still 10 BHN, irregardless of how that hardness is obtained.
The measuring of hardness is best used as a guideline to determine suitability of an alloy in conjunction with pressure/velocity parameters of the load.




Here are a couple of examples to further illustrate:

1. Both the No.2 (5/5/90) and hardball (2/6/92) alloys mentioned above have BHNs @15.
Having nearly identical hardness, both will withstand the same type of pressures/velocities. But rigorous impact testing will reveal the No.2 to deform more before shedding weight.
(This is testing at the extremes- high velocities and hard impact mediums- to determine integrity differences between the two alloys, not necessarily replicating actual hunting conditions.)
Although both alloys perform the same on the firing end, the differences in composition may provide different results on target, but remember that anything detrimental is usually only noticed at the extreme parameters.

2. 20-1 lead/tin has BHN @10.
But if you take WW and cut it equal with lead (50/50 WW/Pb) and add half a percent tin, you're again getting very close to 10 BHN.
So now you have your "poor man's 20-1 alloy".
One alloy has plenty of tin and no antimony, while the other has very little tin and does indeed have antimony (albeit a minor amount). Both alloys are approximately the same hardness, but is there a noticeable difference between the two concerning alloy integrity? Not really!

Several years ago I had the same questions you asked, so I did a little testing.
Using Lyman's 457122 (330grn HP), I concocted similar loads with both alloys (20-1 versus 50/50 WW/Pb + Sn) and spent a day firing into wet newsprint.
Both alloys expanded readily at impact velocities as low as 1000 fps, and exhibited similar expansion and weight retention. This trend continued with velocities exceeding 1500 fps.
Not until I pushed them past 1800 fps did the 20-1 show a significant advantage, in which case the "diluted" WW started shedding slightly more weight. BUT, who uses a 10 BHN hollowpoint bullet at those types of velocities?

in an antimonial alloy you need the tin to strengthen the alloy. SbSn is a far stronger chain than the "just enough tin to fill out" alloy.
as pointed out above.
what the SbSn chained alloy does for you is alloy you to use much less of both, to achieve a harder stronger alloy.
the way i think of this is malleability vs hardness lead is malleable,antimony is brittle,and tin is tough yet flexible.
a combination of all three acts one way a combination of just two is another thing alltogether.
lead and antimony is swageable, add tin though and it is too hard.
lead and tin makes a nice malleable casting alloy that retains weight under stress, add antimony and the boolit can shatter or break under stress.
but a COMBO OF ALL THREE, can have all desirable traits, or too much of one trait depending on the mix.

Thanks for the info guys. Mainly I will be hunting hogs (all year) and deer (in season) with my 41 mag starting out with Miha's 200gr HP. Probably at about 11 BHN. If that does not do what I want, I wll switch to a 220 or 240 grain at probably the same BHN and see how they do. Either with tin/lead or with ww/pb to that hardness. I will probably be running them about 1150 - 1200 fps. Or should the soft points be a bit harder?

I've shot my cast HP both from 50/50 ww/lead & 25-1 lead/tin. WHile they do exhibit sim expansion abiliteis at lower vel, higher vel impact seem to favor the bullet w/o any antimony.

the higher antimony usually tends to tear the petals off,or not open properly.
for hogs i'd take the penetration.
for deer the smush and penetrate.

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Originally Posted by giz189

Thanks for the info guys. Mainly I will be hunting hogs (all year) and deer (in season) with my 41 mag starting out with Miha's 200gr HP. Probably at about 11 BHN. If that does not do what I want, I wll switch to a 220 or 240 grain at probably the same BHN and see how they do. Either with tin/lead or with ww/pb to that hardness. I will probably be running them about 1150 - 1200 fps. Or should the soft points be a bit harder?

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What you want to do is find the alloy where you have the best accuracy and very little leading in the bore.
Soft boolits from a revolver can slump and deform so much you could possibly close up the hollow point.
I would suggest 50-50 WW's and pure with a touch of tin. Oven harden them to about 20-22 BHN and use a gas checked boolit. That should give you expansion with a ductile boolit without losing penetration yet be accurate. Your target velocity should be just right.