The UK's Finest Independent Forum for Shooters and Gun Owners. Est 2010.

I want to put windage adjustment onto my .22" No.4 rifle. The rifle itself is set up as a C No.7, except for not having the windage knob as the Canadian rifle does. See here: http://www.rifleman.org.uk/Enfield_Rifle_No.7-C.html

I was going to order the parts from the Marstar website (here http://www.marstar.ca/dynamic/category.jsp?catid=78325) but they're sold out of the adjusting screws. Fair enough, thinks I, how hard can it be to find a similar screw in the UK?

Well, that's where I ran into problems.

I don't know the spec of the screw thread. The only information I can find on the screw thread spec comes from the Rifleman website's rip of the Canadian parts manual for the C No.7...

1005-21-106-8981 Screw, Special, Adjusting, Leaf. No 5 – 40NC – 2, 1.45 in. lg. 1 B1-801 35907

I know the 1005 number is the NSN, so useless to me. But does the 40NC figure mean anything? Obviously the screw's 1.45" long, but I don't know what the final figures mean.

The same document has slightly more info about the windage knob, which seems to give the thread spec - not that I can make head or tail of it:

5355-21-106-2129 Knob, Rear Sight Traversing. Knob, round, S, anti- rust fin, 0.410 in. (10.41 mm) thk, 0.500 in. 1 B1-1582 35907
(12.7 mm) OD, 1/4 - 40 UNC internal thread, grip aid surface. W/O skirt, straight shk, unmarked,
3 detent notches 0.020 in. (0.508 mm) dp on back of knob at 120° intervals.

Can anyone interpret that into something I can ask for from the screw shop round the corner?

It's 4-40 UNC thread Gaz
Specs Here
Quite common in PCs for DSUB connectors etc.

M3x.5 should be close but I'd stick to UNC if possible as the tolerances might be tight.

It is a No 5 x40 UNC thread so you need a no5x40 screw. 5 refers to the gauge which is 1/8" and the 40 is threads per inch.

Hmm... well I still read this as 5-40.

ovenpaa wrote:It is a No 5 x40 UNC thread so you need a no5x40 screw. 5 refers to the gauge which is 1/8" and the 40 is threads per inch.

Which will give approx 1 MOA per click, if my fag packet calcs are in the ball park.

..

From memory this is the same as on the Pattern 1914 fine vernier elevation screw.

So I'm asking for a No.5x40 UNC screw? Thanks all. I'm expecting it to be 1MOA - fairly sure that's the elevation adjustment on the C No.7 rearsight.

Yeah sorry, TL;DR No5 it is

I can put my hands on something to suit if you get stuck Gaz.