I had posted earlier about accurizing lever guns but all they need is to have the magazine tube "untied" from the barrel. As the barrel heats up it wants to expand and if it's joined tightly to the mag tube that adversely affects accuracy.

That Marlin I posted above would string shots 4" high when I first got it. The mag tube was wedged solid on the barrel stud supporting it. All I did was enlarge the hole just ever so slightly so it was a slip fit, then made sure the two screws on either side of the forend cap had light and equal pressure and it started grouping as shown.

Same with Model 94's or barrel band .336's. Make sure the front barrel band isn't constricting the barrel and give a little room under the rear band and most all 94's and 336's can put several shots into 2" or less, sometimes much less.

There was an article in an old Gun Digest, I want to say the 25th Anniversary edition, where they tried different things to see what would make lever actions shoot. They even put a match grade heavy barrel on one and it shot almost as well as bench guns of that era. The main thing, though, is to give the barrel some clearance to move where it wants to.

Gunnery, gunnery, gunnery.
Hit the target, all else is twaddle!