i shoot nothing but hard cast from my 45 Colt... mainly because i cast my own and it is cheaper than buying "premium" bullets... my hunting loads consist of 290 grain hard cast with a big meplat moving at right around 1200 fps (22.5 gr of H110)..

the issue i find with nosler handgun partitions at these velocities (less than 1500 fps) is that they won't open up... in 45 cal they are meant for things such as the 454 casull...

a hard cast if too hard will break apart and yes if soft will lead and mushroom... but in the high teens to low 20's brinell they will get some deformation and they will punch a deep long WIDE wound channel because of the flat point (meplat)...

if you want hard cast with expansion you can put a pan of water in the oven.. put your bullets in the pan with water covering up to the crimp groove... leave the tips exposed to the heat... heat them to 350 - 400 F for 30 minutes or so... let them cool and the points will be soft...

if you want them hard... knock them over into the water and quench them