1903 Trigger guard screw tap size

[Allen Humphrey]

A little help please. I need to chase a thread in the receiver where the trigger guard screws go in. Are they 1/4-28NF ?

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[Chuckindenver]

i belive 1/4 x25,,,ill check my notes and let you know for sure, careful,,,easy to blow that hole right out.

[Patrick Chadwick]

i belive 1/4 x25,,,ill check my notes and let you know for sure, careful,,,easy to blow that hole right out.

You're right!

[Allen Humphrey]

1/4-25??? why the heck would they do that to me? I'm not even sure where to look for a tap of that pitch. They sure picked some odd threads (by today's standards). The ding is really just on the lead in thread, so it should clean up ok. Probably could force the fastener in and still work, but I'm not gonna.

[Patrick Chadwick]

1/4-25??? why the heck would they do that to me? I'm not even sure where to look for a tap of that pitch.

I'm sure Chuck will tell you where you can get such oddities, if you really need one. The price will probably make you cry.

I only responded so quickly because I actually had a list of such oddities in front of me, literally between the keyboard and the screen, and was racking my brains wondering why on earth the M1917 has 1/4-30, and where the heck did I park the 1/4-30 tap and die - I actually found a pair at a boot sale in the UK, and don't reckon I have much chance of ever finding one again, certainly not here in metric country.

And be glad you're not looking for Enfield screws!

[Patrick Chadwick]

am afraid to see what the 1/4-30 might be!

Probably a pound per thread! This thread was used on No. 1 Enfields, but no longer on No. 4s, so the chances of finding one new are approximately 5/8 of FA, as British engineers like to say. Maybe one can get them in Australia or India?

Probably could force the fastener in and still work, but I'm not gonna.

Allen, you need to apply a bit of backwoods engineering!

The old trick for cleaning up a threaded hole, IF you have a spare steel screw of the correct thread, is to file a little slot down the side, to make it look like a self-tapping screw, harden this screw, and then use it as, in effect, a simple one-fluted tap.

If you do not have a spare (a common situation with rarities) then do basically the same with your one-and-only, but file the slot just though the first 2-3 turns, and do not try any hardening! This is usually good enough to reform a burred thread. Better than brute force, anyway!

Patrick

[Allen Humphrey]

1/4-30, that sucks but misery loves company Brownells has the 1/4-25 taps for approximately a dollar per thread. I am afraid to see what the 1/4-30 might be!

Thanks Patric and Chuck.

[Allen Humphrey]

Hmmm. Home made tap. We call that Farm Tech around here, but it would probably do the trick. I don't have a spare, but they are around and I can grab some at the next show I suspect.

I'll bet your 1/4-30 taps are lying around India by the gross somewhere, and my 1/4-25 is probably knocking around Greece.

[Chuckindenver]

check MCS they have any tap size you want...price wont be too bad...id bet around 50.00

[Patrick Chadwick]

Chuck, thanks for the tip, but could you please be a wee bit more precise? It's a big wide world out there on the internet.
I found an MSC Industrial Supply Co. that has about a thousand different dies, and thousands of taps*, but not an MCS that made much sense.

If you did indeed mean MSC, then they even have a 1/4-30 die! But no 1/4-25 that I can see.

Patrick


*Not a joke or exaggeration. Look it up! 1750 dies. 17570 taps.
In 1/4" diameter you can have 18,20,24,27,28,30,32,36,40,48,56,72,or 80 t.p.i. !!!
But no 25 tpi.