I have little experiance with the rimless DR chamberings. One that I did have was with a Chapuis in 375 Holland. The springs that allow the leafs to go down as the cartridge is fed in the chamber and then pop up into the groove at the base are so tiny that it is hard to even pick them up with your fingers.

On this particular rifle the springs would break and the leaves would not pop up in the groove. Thus the extractor would come back but leave the shell in the chamber. The owner replaced the springs twice. Both times he replaced both springs to be safe. He finally gave up and sold the rifle.

I also think that quite allot of people will be tempted to Hot Rod a rimless cartridge to try and obtain maximum velocity. There used to be a poster here who always claimed 150-200 fps better than listed velocities.

The DR's he sold were always off face, something he rarely pointed out or perhaps never noticed.