Pure lead is generally the most sought after stuff, because as was stated, for muzzle loading the patch has to engrave right into the ball to transfer te twist of the rifling.
In cartridge guns it is sought after as 32-40 said, because we like to be able to keep as consistent a mix as we can when making our bullets .
This has much to do with the accuracy, too soft is not good, neither is too hard, and a some bullet will have a different point of impact than a hard one, both in muzzle loaders and cartridge guns.
For casting shot, many shooters use straight wheel weights, but some like a bit harder alloy of pure lead shot added to the wheel weights.
So after all this, yes, pure led is the best to barter, sell, and trade with!!
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