Never had a single issue with the .243 here. Piles of whitetail and a fair number of black bear. It was my main cartridge for years, and still carry one quite often now. Wife uses it exclusively, several of my hunting buddies use one, and it gets the nod when we take new hunters.
Most kills either with 105 Amax or 95 NBT. Have saw a ton drop with various 100 gr factory offerings as well. Have one buddy who uses 55 grain BTs and loves them. Says they’re the best bullet he’s used for neck shots.
Whatever issue you have, it’s not the cartridge. Scratching my head as well about bullet issues, if they are breaking both shoulders like you stated in your post.
