Lapping a rolling block barrel

[Abert Rim]

I have a nice old Husqvarna Model 1867 in 12.7X44 that was sporterized in Sweden long ago. Those of you familiar with these Swedish rolling blocks know the barrel grooves are incredibly deep. The bore on my rifle has some fairly significant pits despite being mostly shiny. I am wondering Just how much lapping I can get away with before accuracy is affected. In other words, if the lands and grooves remain uniform and symmetrical but the edges of the rifling loose their crispness, won't the barrel still impart all the needed spin for stabilization? I will of course use soft lead bullets and BP in loading for this gun.

[felix]

For lead, deeper is better than sharper. ... felix

[Nelsdou44]

I have hand-lapped a military 7.92 barrel that was badly pitted, more for the experience and experiment than anything else. Although the lapping did not eliminate all the pits, it did significantly improve accuracy and cleaning. There are several good descriptions of how to hand-lapp with a lead billet and grinding compound if you do a google search; much better than what I can describe here. If you stick with fairly fine grit (320 or so) the metal removal rate should be slow and controllable.

Nels

[Buckshot]

..................Abert, I wouldn't bother lapping it unless you've shot it to know it NEEDS lapping.

..................Buckshot