M1881 38-55 screw

[DrDucati]

I loaded up some 38-55 BP rounds and shot em in my Marlin for the first time. Action is smooth and seems to hit where I aim, though I wasn't set up to really check accuracy.

I'm cleaning it and taking it down at which point two things happened

1) my heart sank when I saw a ring about midway down the bore. How bad is that supposed to affect accuracy?

2) The dust cover screw came out alright, couldn't get it back in; in fact it turned to mush and the head came apart. I'm using appropriate hollow ground tools. I suspect it was some sort of replacement. So I wonder if anyone here who owns an M1881 can check theirs and measure the screw for thread and pitch diameter for me? Then I can buy or fashion a replacement. I believe I will need to retap the hole for that also.

[country gent]

How bad is the ring and is it a ring or just a dark spot? I have seen barrels with rings/ bulges that shot good still, and others that were ruined. A lot depends on how heavy big they are and location of them in the barrel. A good look in it with a bore scope may tell a lot.

Check gun parts corp West Hurley New York. Their schematics and parts lists may give screw size, or they may have one on hand.

[DrDucati]

Thanks gent. as often as I get old guns probably worth getting a bore scope. It's a thin ring that a can feel when I run a jag through the bore but not sure how deep it is.

[ulav8r]

Had an instructor at CST that had a .22 whose barrel had 4 very noticeable bulges along it's length, one was only about 2 inches from the muzzle. He said it still shot very good groups. A bulge does not automatically mean a barrel is no good.

[DrDucati]

Had an instructor at CST that had a .22 whose barrel had 4 very noticeable bulges along it's length, one was only about 2 inches from the muzzle. He said it still shot very good groups. A bulge does not automatically mean a barrel is no good.
Mine has no bulge. It's an annulus-shaped pit, but I understand your point.