How safe is to shot cast bullets on a 1911

[Sam1911]

but the 625 leads up it prefers jacketed bullets

Did you measure your chamber throats? They'll want to be .452" or maybe .453" and it's pretty simple to have them reamed to that if they're a bit tight.

Having the throats size the bullets down to smaller than bore size before they jump the cylinder gap and enter the forcing cone makes leading pretty hard to get rid of in a revolver.

I had my 629 reamed to help eliminate all leading.