BSA rear guard screw size? Superstar, Meteor etc

[Phil Russell]

Can anyone confirm the thread size of the rear trigger guard screw for a Superstar / Meteor and other models? I am carrying out a little cosmetic work on a Superstar and the screw is a bit 'challenged cosmetically' although does work. I have tried various screws from my collection but failed to find a replacement. Searching around on this forum and the internet in general leads me to the conclusion it could well be UNF 8-36.
I know I could buy a new one but that irks me a bit although to be fair, a search for unf 8-36 screws shows they are not very cheap anyway.

I am told you can re-tap to 2BA but I see no need to do that. It might be more fun to get a 8-36 die and cut a new thread on a slightly oversize screw.

Interestingly the front stock screws can be replaced with 4mm although I doubt that is the original size.

All help appreciated.
Cheers, Phil

[piggy589]

Two bee eh all round.

[Strimmer]

I tried googling this a while back and just bought (last week) of John knibbs. Think it was a fiver posted. Like you I tried dozens but I'm not technically minded so just bought that incase I screw the thread up

[Phil Russell]

Two bee eh all round.

Sorry but they are not. I tried a 2BA bolt in the rear guard just to see and it is not the right size. I found a thread somewhere that informed me that the manufacturer's thread could be retapped to 2 BA quite easily though. Maybe that is what you have come across. And the front stock screws are certainly not 2BA. 4mm fits but I doubt if that thread form is the original spec.
Cheers, Phil

[evert]

M5 in my Supersports and Superstar. Thats the rear trigger guard screw, the fronts are M4.

[Phil Russell]

This is getting more puzzling. Thank you evert. I tried M% but it was too big ... pity as I have a lot of them.

I am wondering if the best solution is to strip the action and re-tap the thread.... and put a nice screw in place.
Cheers, Phil

At the same time ... if someone has an electronic version of the Owner's Manual, I would be very pleased to have a copy.
Cheers again.

[evert]

This is getting more puzzling. Thank you evert. I tried M% but it was too big ... pity as I have a lot of them.

I am wondering if the best solution is to strip the action and re-tap the thread.... and put a nice screw in place.
Cheers, Phil

So, after making this duboius assumption based on memory and a bunch of mixed up supersport parts, I realized that my contribution would just add more confusion. So I went and actually measured some screws on some guns:

Late Supersport (presumably Birmingham made):
Rear: M5X0,8
Front: M4x0,7

Early Mk2 Supersport and Superstar:
Rear: measures in at about 4,6mm, and the thread pitch is VERY close to 0,7, and does not match up with any of my TPI gauges.
Front: M4x0,7

I measured a mk3 Meteor too:
Rear: the same as the early Supersport and Superstar
Front: not measured today, but earlier confirmed to be a 2BA (I actually made some screws that I threaded with a 2BA die for a meteor a while back.)