Lead vs Bismuth in reloading

[J.B. Books]

Originally Posted by Matt Valinsky

I have not used Bismuth for reloading and have no knowledge of the beast, so the reason for my question.

I have found a 16ga. recipe which I have all required components, Cheddite hulls, cheddite primers, SG16 wads and Green Dot powder. In this particular recipe the playload is 7/8oz. of Bismuth which I don't want to reload, I would rather use 7/8oz. of lead. I have read that all things being equal that 7/8oz. of lead will generate lower pressures than 7/8oz. of Bismuth. from what I understand it's a volume thing.

So, my question to the folks who know the answer, is this true?

In the Bismuth recipe with 15.5 grains of Green Dot the average velocity is 1221 fps and average pressure is 5803 psi., this is a tested recipe.

Thanks in advance.

Bismuth delivers higher pressures than lead, because with equal weight there is more bore scrub (friction) as the same weight of bismuth has a larger volume.

An old rule of thumb is you can take any lead recipe and substitute the same VOLUME of bismuth and get similar results. If you should do that you are in untested territory but I have never heard or read anyone who had a problem by doing this.

If you substitute lead for bismuth in a tested load in theory there should be less pressure, given the very low pressure of your chosen bismuth load substituting lead may lead to bloopers and squibs especially in cold weather.