joe348,

Welcome to the enjoyment of old gun threads!!

First, if you are going to mess around with reproducing old gun screws, I'd suggest purchasing a thread pitch guage that will measure from about 4 to 84 TPI (Starret No. 472 or similar). Second, consider a thread mic so you can measure minor diameters from your existing screw samples.

One problem you'll face is that U.S. screw threads weren't really standardized until the early 1900's, and before that, they made whatever the hell they wanted to, and in some cases, they intended the sizes to be proprietary so you pretty much had to deal directly with the manufacturer for replacements.

Expect a lot of non-standard sizes in both what we refer to as number sizes (#6, #8 etc), and fractional sizes as well.

Bad news is, taps and dies will usually be a special order, but you can get a discount when you order by the dozen. Some outfits have a good variety of the old threads available but you have to dig.

For your takedown screw, 5/16" x 30 tpi is a good match.
Try 5/32" x 30 tpi for your hammer screw.

Have fun!!

BP

PS: a lot of English (British) lathes have 30 tpi  as one of the selectable threads on the gear change, haven't seen it on many others.

Based on an earlier reply on this forum, Victor Machinery has 5/16" x 30 taps.  In 5/32" they have 32, 36, and 40, no 30 but they talk about custom taps. (You need to Login or Register to view media files and links)  

Have had good luck ordering from Victor
Chuck