The Magtech factory ammo may indeed be too hot. It isn't the first time I've heard that about Magtech, but that's just secondhand info and allegations.
I certainly have no objection to Hank08 shooting whatever he wants to in his guns, and I don't mean this as a personal criticism of him, but I think it is bad advice to recommend using .45 Colt brass in a FA .454. Chambering problems and higher pressures due to lead and crud build-up are well known phenomena resuting from the use of that brass in FA's, whether a particular person has experienced it in one gun or not. I've done it as a test, I won't do it any more, and I won't recommend doing it.
You've received plenty of good advice to clean your chambers well, then change ammo. If I was you, I'd take that advice, and see what happens.