I might also add here, that a full calibre projectile is much more efficient a killer, than sub-cal bullets. Having a stable projectile of .50 or .54 cal is much better than the longer/for/calibre heacy pistol bullets.
: As I see the situation, most of the inlines or fast twist guns have twists right down to 28", but that's about it. In .50 cal. this will stabilize bullets to about 600gr. In .54, probably 700gr. so standard bullets in 400 to 500 gr. will work perfectly. The .44 and .45 pistols bullets weighing 300gr. and just over, require 18 to 24" twists for stability after contacting flesh. Because they do seem to work fairly well, lots of people use them, however they do diminish the power of these large calibre rifles from what they are capable of. The 50-90 was a preferred rifle for big game like buffalo and elk because it was a faster killer of those animals. If you have a .50, then it's greater power really should be taken advantage of. The smaller .40 and .45 calibre buffalo rifles were only superior past around 400 or 500yds., the accuracy limit of the .50 cal. rifles of the day. This is well past the range anyone should be shooting at live animals today.
: I have always leaned toward a soft lead projectile rather than some 'fancy' highly advertized modern projetile because the lead bullets work in all rifles.
: As I understand the situation, the front part of this belted bullet doesn't engrave the riflng, or upset- that is the job of the plastic base. If your bore size isn't perfect for this fancy bullet to hold it in perfect alignment with the bore's axis, it will be either too tight or too loose, and either will cause problems. At least, if they do work, they are a step in the right direction, being bore size. I suspect without lube, or a place for it, they may be difficult to load after a couple shots- if, the bullet is a tight fit to the bore, and it should be for adequate accuracy.
Daryl