For the 450 I'm talking about the initial sizing of new brass. I had 10 new old stock BELL cases, marked 450 Base. These took a lot of effort to size down in their first pass through the CH4D dies I purchased. Easy to resize after firing, but the first effort was difficult.

Cases lost so far have varied. The one 450 case I lost had a longitudinal split form in its side. Doesn't go down to the base of the cartridge, nor to the mouth.

The 360 BPE Bertram case I lost developed a bend closer to the base than the mouth. I have not tried tapping this out on a mandrel yet. The other 19 were fine.

The 500 BPE A-Square case was purchased used. I created a circular ring in the case just below the mouth, like the muzzle of a Napoleonic wars cannon, when trying to resize the first time.

I have not annealed any of these cases before sizing.

I will definitely try the short stroke and rotate approach recommended above.