Where do you guys get your gunsmithing screws? I need a 10-38 plug to fill a hole the PO D&T in my Marlin 1895 for the rear tang sight which I'm planning on ditching. Also a standard rear tang screw and two 8-40 peep side mount screws. I know I can get these last two from brownells but I can't find the 10-38s...

Winchester used odd sized #10 screws for their sight holes until right after WW2; they are not made any more. I think they were 10-36. You will have to custom make one on a screw cutting lathe. Or re-tap it for 10-32.

damnit. That's going to be fun on our 10' lathe... It's looking like the only option though. The thing is this gun was made in 1989, not sure when the sight was put on but why on earth would someone use such an obscure screw size? Surely they would have had to buy them from somewhere?

Also, re-tapping to 10-32 is going to make for one messy hole right?

if you're just filling a hole why not make a small plug and tig it

Are you certain it is 10-38? I was just looking around for a die, as it might be cheaper to purchase one of those if sold locally than order a special screw and I can't seem to find one.

So where did the OP get a tap to thread the hole in the first place?

Not saying you are wrong, but that for me when something doesn't make sense often one of the bits of information is wrong.

If I was simply looking to fill a hole I'd use dpcd's suggestion of running a 10-32 tap in there and an appropriate screw. Even if I was to re-mount a sight a retapped hole would work just fine and a non-issue especially if loctite were used.

OK I just had my morning coffee and did a slight amount more looking and thinking on this, wondering about this thread size.

It occurred to me with you living in OZ it may not be a UNF or metric thread, but possibly an old British size.

So, assuming your thread count is close there is a BA (British Association) thread that is close:

Screw Numbers ** Diameter of Screw Over Thread** Threads per inch ** Pitch Diameter at Thread Bottom ** Tapping Drill Size

4 BA 0.1420 inch 38.5 tpi 0.0260 inch 0.1108 inch Number drill 31 3 mm 0.1181 inch
3 BA 0.1610 inch 34.8 tpi 0.0287 inch 0.1266 inch Number drill 29 3.4 mm 0.1339 inch
2 BA 0.1850 inch 31.4 tpi 0.0319 inch 0.1467 inch Number drill 22 4 mm 0.1575 inch

A #10 screw is .189" so if you have a BA screw hole it should clean up IF this is what you actually have. I also happened across a comment that BA threads are used mainly for "instruments and clocks" so if there is a business that handles those items they may have some choices for you.

Try this:

http://www.msdiscount.com/colu...set&sessioncookieset

Try :

Victor Machinery Exchange Inc.

www.victornet.com

Thanks a lot for the help guys. I actually bought this gun in the UK so the work had been done there...
I want to be able to keep the option of remounting this at the moment so welding is out (only got mig/gas/arc anyway), also would mean refinishing and the finish is in pretty good knick.
But, it seems 10-36 is a lot more common. I was measuring with calipres and the screw is so short I only had two threads to go off - 38 is .530 and 36 is .556 - too close to tell between for me! So I'm thinking they may actually be 10-36. So these might be easier to get?

Try winding a toothpick into the hole and then inspect the marks under magnification.