Re: mauser 7mm remington magnum
If youre looking for prefit barrel Lothar walther makes some atleast.
If your'e looking for a barrel to be fit by a gunsmith (threaded, chambered etc) you can pretty much go with any good quality barrel maker.
USO can make rails for it, so does egw.
Triggers from CG, Timney, NECG, Huber, Jard and Bold.
Mcmillan can inlet sny stocks for them.