Thread: do projectiles harden

As I understand it aging IE lathe beds etc has more to do with stress relief and gradual realignment of the grain structure than anything to do with hardness but this is cast iron and alloys could be different
Are you sure they are not opening? would generally cause(with a pointed type projectile) a smaller than caliber wound both sides and very very little bruising around the hole.
Is it possible that lately you have been shooting at longer ranges than you used to? The lower impact velocity of longer range shots could turn the perfect pill into a drill bit.
Or have the last few you have shot been lucky/unlucky No bone shots where previously you have always got a bone(even if only a onside rib)
By some kind of error could you possibly have loaded to a lower velocity? maybe a new batch of powder? memory error?

I'm not saying its impossible that they have hardened over time it just seems unlikely to me.