I bought a GM .50 cal barrel for my T/C Hawken .54. The only problem is that the .54 is a larger barrel so when the .50 is ordered with the same across flats it ends up a very heavy barrel. Don't forget your .54 does not have the same size barrel as a .50 if you decide to order a barrel for it. I just wanted the Hawken to be able to shoot both size bullets. Probably never use the .50 but I just had a desire to do it at the time.