Twist it not the problem, but the Ballard rifled barrel's it's isntead.

Hence in a cast bullet, you have to size the 44 mag bullets to .432~.433" to allow them get a good hold and keep that hold on the shallow groove rifling isntead.  It was the same problem with the Micro grooved barrels as well.
Note, pushing 270gr PC hard cast bullets (no gas check) sized at .432" @ 1800fps, and getting 1" groups at 100 yards through my worked rifle: with no leading as well. the ballard rifle barrel  will stablize a full 310s with gas check is over sized correctly, but even more of hand full when pushed isntead.  My fun loads for all around plinking at the same 270 PC bullet at .432" but only pushed to 1200fps isntead (to save my shoulder since the gun is very light to begin with,and after a hand full of full loads, your going to start to feel in your shoulder instead).

As for the rest of rifle, if the action and trigger has not been gone through to do an action/trigger job on the rifle, your dealing with a complete shit show instead.  On the Remlin 1894 I picked up last year, when I pulled the hammer (it's a MIN part), the ledge of sear production grinding for the shelf left a ton of edge burs so bad, I had to mill re-cut the sear edge and surface to clean up the ton of burs. The trigger sear was no joy as well with burs, but it stoned up clean on a just a jig instead.

As for the less rounds in the mag, take a good look at the mag tube, and you can see that is has been been back shortened, and it moved back towards the receiver (with it's barrel band cut out in tow).  So when the barrrel was shorted and threaded down to 16" (from the 20 it comes stock), the barrel was re-bottom cut for the the barrel band in the new rearward location instead.

As for the XS sights, the aperture does not come threaded for a Skinner aperture, but not the end of the work changing it out to a tanner the same time you order one of his apertures as well.

As for the big loop lever, not my thing, and would have been better off with med loop isntead.
Note, for faster cycling on a worked action, small stock loop with leather wrap is about the fastest, with your pinky finger out of the loop instead.

Stock on top, med on the bottom,