Sitting at my bench, I happened to look at my 325PD and a box of Speer 250 gr GDHPs. Hmmmmm.....Placing one of the cartridges against the cylinder (no, it did not fit within....) and....it might JUST fit if reamed out. Reaming the Ti cylinder is out of the question, but I wonder about reaming the stainless cylinder of the 325 Night Guard to 45 Colt?

The 45 Colt measures 0.480 at the head; the 45 ACP is slightly smaller at 0.476 in. The cylinder width of my 625 in 45 Colt measures 1.710; the 325 PD measures 1.718. The 625 cylinder wall is 0.068 thick over the cylinder notch; the 325PD is 0.074 inch.

The 625 MG cylinder is 1.670 inches long; the 325PD cylinder is 1.541 inches long.

The 250 gr Speer GDHP measures right at 1.530 inches from the inside rim to the bullet nose. The width of the 45 Colt rim is 0.580; that of the ACP is 0.573.

So, AT A SUPERFICIAL LEVEL, the conversion looks feasible. Thoughts?
Or has this already been tried and failed/succeeded?

I'd contact some serious gunsmiths (e.g. Bowen, Stroh, etc) and get their thoughts on it. If they say it's feasible, great. If not, I would chalk it up to a nice idea but refrain from trying it at home. JMHO.