I think Zimhunter said it well.

I will add that messing around trying to get my Marcel Thys sidelock 458wm SxS double rifle to fail A) didn't work, it has been flawless B) makes me think that for a rifle chambered for belted cartridge the head spacing would have to be excessive to leave enough slop in the chamber for the cartridge to go so far forward that the clip could slip over the rim when the rifle is closed.

I could see how an improperly resized case which head spaces on the shoulder could possibly cause problems, not so with a belted cartridge.

If the clip is inoperable, it should be apparent when the rifle is loaded, prior to closing the rifle, prior to going hunting. Seems to me that, like any other rifle, a broken rimless double rifle ought to be fixed. The possiblity the the clip becomes inoperable between, say, the second and third, or fourth and fifth shot at a dangerous game animal seems too remote for consideration. I do keep the clips and other extraction and ejection pieces clean though.

Pressure issues are no big deal. I don't doubt that for any given quality of rifle, meaning quality of fitting barrels, hook, bites, lumps, etc, a high pressure cartridge will cause a rifle to come off face faster than a low pressure cartridge. The higher the quality the longer the interval for any rifle in any chambering, of course. In my experience a high pressure cartridge will lead to decades of service before a rejointing is required, but my rifle is very high quality. Even so, putting a rifle back on face is cheap and easy to do, its just no big deal.

I think proper care and lubrication is more critical to rejointing interval for any rifle than the chambering.

Hopdoc,

You should be looking to an ejector rifle for DG hunting, imo. Still, extractor doubles in rimmed cartridges have been in the action for a century and more. I definitely would not look at a rimless extractor rifle, for a couple of reasons, including the one you point out.

JPK