Well contact Berger because you've had more fail than any single person I know and your having repeat issues, heck maybe you can figure it out. I have one single Berger not open and it was a hit through the flank that hit nothing going through, it would have taken a varmint bullet to open. We tried to push the 300 gr OTM to find the low end and we had a very light hit through the ribs on an antelope, hole in the lungs were about an inch so it looked to open a little same range on elk and it opened every time. I've witness my buddies 338 RUM shot 5 elk and three antelope with the 300 OTM a couple close and the others in the 800-1100 range and the wound channels have been constant with the hits, all one shot kills but only one was shot through any heavy bone just ahead of the shoulder in the neck which nearly decapitated it, the rest all went through the slats, they just wobble a few steps then fall on their nose or flip over, all have exited.
I'm not saying this to appose your view but why the heck can one guy have kill after kill with easy one shot dead then another have half of them go to hell, could it be traced to an issue in a lot or one press or bullet die set or we have shot different lots. Could it be the different shot placement, heck I don't know, I find this as frustrating as you cause if I can't nail down a reason then maybe it will happen to a guy I recommended them to and I hate the though of that.
I have not caught a 300 gr Berger in anything alive, you have several, what's the difference I should have had an issue based on the number of animals hit, been watching for it to happen since the one you had at 1400+, in fact after talking to you about that I've dialed in my gun for the shot to back the 338 up if needed but never have, but most of our kills will be with lighter cals and the 338 only when we can pull it and have time for setting up the ground cannon.