Any of the barrels (except some of the newest being make for the G2) should fit any of the frames. Lots of possible reasons, but two biggies.
If you're shooting reloads, try it with factory ammo. Your overall length could be too long causing your "hard to close" problem. Second it could be a bolt height problem (bolts fit in the lug and are spring loaded. You can fix it yourself or TC will fix it for you.) There've been some good explanations on this forum that I won't try to duplicate ('cause they did a better job than I could ever do). Use the search function to find them.
Helobill