For those who do not know, California has banned the use of Lead in ammunition used for hunting. Why? Supposedly to reduce toxicity in birds eating lead lumps and shot. In reality, more likely IMHO is that the goal was to make it harder to get any ammo to shoot and raise prices.
The result has been a lot of use of Bismuth in shot as the weight is about the same as lead and it is non-toxic. Also it isn’t that expensive. For hunting rounds in rifles, the use of solid copper and related alloys has been common.
Copper is much harder than lead, so many of those hunting rounds now penetrate more soft body armor than the prior rounds. (Note: NO soft body armor is “bullet proof”, each is only rated to stop certain classes of rounds. There is no “bullet proof vest”. There is no “cop killer bullet”, only a necessary energy and hardness to penetrate any given level of vest.)
But what happens with a Bismuth slug?
Well, the Taofledermause folks tested it. Results are fascinating to say the least. Due to increased brittleness, the slug tends to disintegrate on hard targets. BUT it also tends to make a few larger chunks in the process on softer targets. As a result, it penetrated a Level 3 soft body armor test panel that will stop a Foster Slug of lead.
In a block of ballistic gel, it was an amazing effect. Shedding some fragments that stopped in a few inches, while some large chunks traveled the whole length, and the rest formed an expanding cone of destruction in between.
I would not want to be on the wrong end of one of those slugs.
Now, this was an alloy of mostly Bismuth, a bit of Antimony, and some tin (12%) so as to stop the tendency of Bismuth to expand on cooling. That let them use a regular lead casting mold to get a proper sized bullet / slug. I have no idea how much of this peculiar performance comes from that particular alloy, but it will matter to some degree.
Bismuth - 87.25% Antimony - 0.75% Tin - 12%
An interesting result, to say the least. Attempting to make it a pain to go shooting your shotgun resulting in a spectacular increase in lethality. Leftists – Accidentally increasing lethality for 53 years… (Banning “Saturday Night Specials” moved uninformed shoots / buyers up caliber and up quality into more lethal guns and calibers…)
I’m no longer concerned about the effectiveness of Bismuth in shotgun rounds ;-)