I must agree with JPK, partially that is, on the lubrication, being more the grimlin that causes the "OFF FACE" condition than high pressure! I would say a full 90% of the off face doubles is because of poor care, rether than overloading.

The problem is a full 90% of the folks who have never owned a double rifle, and start by buying a rimless, or rimless belted cartridge start by thinking they can boost the velocity considerably. This is simply the mindset of most who are attracted to rimless belted magnum cartridges, and have been used to bolt action rifles, and do not fully understand double rifle feeding. This misunderstanding, and poor lubrication combined is death to a double rifle.

The main drawback to a properly loaded, and lubricated double chambered for a rimless, or belted rimless cartridge is, the chance taken in the loading, and extraction/ejection mishaps causeing the shooter a problem at a very inopertune time! JPK, shoots a 458 Win Mag double rifle, and he seems to have zero trouble with it in any way. Still, I for one, of many double rifle shooters will not have a double rifle chambered for such chamberings, that is to be used for dangerous game! Smaller theings like deer, no problem, if it fails to load, or eject properly nothing is lost more than a missed chance at a shot! OTOH, if the same thing happens with a Cape Buffalo, or Lion closeing on you fast, ..........well