Going no hollow point with frontal area, the smaller the frontal area, the faster it will need driven to expand.
If not hollow pointed, I do not expect any expansion out of 45ACP and definitely not from a RN 38. Hollow pointed they work much better.
Remember, swaged bullets exist for these rounds even in flat nose shapes and they do not expand at all unless contacting really hard material, something flesh really is not.
For non hollow pointed flat nose 45s, 1100 fps impact speed is where they start to mash; perfect for the big 45/70 and muzzleloader and hot 45s.
Having used the 45/70 with a 340 lbt softnosed from a 1895 Marlin and a 300 LBT wfn 44 Mag softnosed in a Marlin 1894 on 4 deer, they expand, knock em flat with lengthwise exiting on two of them. The others easily exited with broadside shots.
Generally the nose will blow off somewhere on a lengthwise shot, just like a Partition.
Its interesting you asked about this. A friend wanted to try some of my 250 softnosed 35 Whelen loads. They shot better than his 225 XLCs he used last year. He shot a deer Saturday with it with a front quartering shot tha exited the left rear him.
Granted those clock 2,500 and the impact speed is up there, but boy they sure work! Its hanging in the meat shed as we type.
Once we start cutting, maybe I can post up some post mortems.
