Hey guys. I saw a post in the Percussion Rifles section of The Muzzleloading Forum by a guy who bought a GM .54, 1"x32, 1:70 replacement barrel for his Renegade from the Log Cabin Shop, Lodi, OH. During cleanup following his first range session he discovered the nipple was M6X75 thread, and the breech plug was threaded for the standard TC 1/4 X 28 nipple.
I just got finished checking the .54 GM barrel I bought last month from Track Of The Wolf, AND FOUND THE SAME THING. The nipple starts to wobble in the threads after the first 1/4 turn out. Not a good thing. I just finished sending a notice to TOW and GM.