set trigger adjusting screw for 1850's vintage triggers

[mountainman70]

Hi Friends,I need to get  the above mentioned screw for an orig gun.Not sure of what thread pitch,size.Any suggestions would be appreciated.Friend in another state needs em,no local hardware or? stores near him.Thanks for your input,have a goodun.Dave F

[Dave B]

The first thing you need to do is make a pattern of the existing threads to get an Idea what the pitch is. It may be possible to use a tooth pick (round kind) to run into the existing threads. I used a scrap bit of hickory scrap. Whittled down to start in the hole and screwed down to where the screw threads are clearly marked on the shank. Just use a thread pitch gauge to find the correct pitch. This can also give you a rough guess as to the shank size of the screw needed. There was a example of the use of a soft Iron steel shank made square tapered to run into the hole. By tightening the screw shank the existing threads start to bite the  the square edges leaving the spacing so the pitch can be determined. Its allot easier if the triggers are out of the gun. The screws used in the Davis set triggers are 3-48 according to the TOW catalog. I just checked several of original set triggers from that period and two of the three I  have were using the 3-48 size screws. One of these was missing a screw and a Track of the Wolf replacement 3-48 screw went right in. The other one I have used a bigger and courser screw which seamed closer to the 4-40 or 5-40 size.

[Bob Roller]

The first thing you need to do is make a pattern of the existing threads to get an Idea what the pitch is. It may be possible to use a tooth pick (round kind) to run into the existing threads. I used a scrap bit of hickory scrap. Whittled down to start in the hole and screwed down to where the screw threads are clearly marked on the shank. Just use a thread pitch gauge to find the correct pitch. This can also give you a rough guess as to the shank size of the screw needed. There was a example of the use of a soft Iron steel shank made square tapered to run into the hole. By tightening the screw shank the existing threads start to bite the  the square edges leaving the spacing so the pitch can be determined. Its allot easier if the triggers are out of the gun. The screws used in the Davis set triggers are 3-48 according to the TOW catalog. I just checked several of original set triggers from that period and two of the three I  have were using the 3-48 size screws. One of these was missing a screw and a Track of the Wolf replacement 3-48 screw went right in. The other one I have used a bigger and courser screw which seamed closer to the 4-40 or 5-40 size.

I don't know about antique trigger screws but on my new ones I use a 2x64 for adjustment and 6x40 for the mainspring which also captures the front trigger tension spring.IF either screw is ruined a "Next size up"can be
used by rethreading the holes. The 2x64 can become 3x56 and the 6x40 can become 8x32.

Bob Roller

[GrampaJack]

I have successfully used brass rod to determine the pitch.  Most of the time for a very small screw 1/16th inch can either be used directly or gently filed down until it will start.  It might also be necessary to anneal it to make it easier to go in.  Pliers can usually be used to do the turning along with a little lube.  I have had times when the brass trial rod became the permanent fix if there was not a lot of force required.  Be careful, breaking a soft brass rod off in such a small hole can be a vexation to the spirit. Jack