My M1917 was produced between Dec ‘18 and Jan ‘19, and really hasn’t been shot that much.
The rifling is very sharp, but the bore is very pitted. Evidently, they just proofed these “postwar” guns and stacked them up to clear the contract. It’s rough enough to pull lint out of cleaning patches!!!, so I use a bore snake.
I was a bit concerned about this, and the first few times I shot it, I held it well away from my face, but the brass and primers looked OK. The stock has been chopped, the barrel channel free floated and the action bedded.....and if it can hit T-posts at 200 yards every time I do my part, I can claim MOA performance. Go figure. It’s old and ugly, but gets the job done, sort of a reflection of it’s owner!
you can lap a bore with valve lapping compound on tight fitting patches or you can load up real light loads and coat the bullets with valve lapping compound...or a few companies sell pre coated bullets for bore lapping...this should be done judiciously as you only want to smooth out the bore and not take off so much metal as to lose accuracy.
http://www.davidtubb.com/final-finish-tms
my Winchester ‘73 had extremely light rifling...I assume it was shot with corrosive rounds...put away dirty and then eventually shot again...the barrel was probably just a rusty hole...and when shot again it cleaned out the rust and most of the rifling....the chamber was also enlarged...
I slugged the bore by driving a larger lead bullet down the barrel with a rod and mallet and measured the bullet with a micrometer and what should have been .427”(the old .44 were .427” as oppose to modern .44s which are .430) the bore measured .432” at its tightest point...I cast some bullets out to .432 but they were not as accurate as store bought .431” bullets from Oregon Trail.
with the almost shot out bore I am able to group 3” to 4” at 100 yds....more than accurate enought for most uses that an enemic .44-40 should be used for out to 100yds...
at cowboy action shooting ranges it always rings steel...
and I poured thousands of smokeless rounds through my almost 130 year old piece.
good shooting.