The shorter barrel kinda doesn't worries me. Being an older fella with short legs, it is real nice to carry the X7 around whilst hunting. The short barreled thing killed some doe last season.
The load we settled on is 105g BH209, Winchester 209 primer, Crush Rib Sabot, and various 270g to 300g bullet in 44 and 45 caliber.
The .44 300g xtp was clocked by a chrony at 1875 fps from the X7. From the longer barreled Accura the same load, with a different sabot, was clocked at 1960 fps. Obviously, barrel length is not an issue.
The killer bullet last year was the 300g Nosler Partition. This year we are starting out with the .44 270g gold dot, just because.
We used a scope to refine our loads, but are required to use iron sights during the muzzle loader season here, so the X7 is perfect.