BSA rear guard screw size? Superstar, Meteor etc

[Phil Russell]

Having stripped the relevant block out, I find a 2BA screw fits. Why a 2BA would not fit with the block assembled on the rifle in the first place I do not know. if this thread is really 2BA then it could explain the untidy appearance of the guard screw fitted. Maybe this screw was forced into a 2BA thread???
Whatever ... onwards.
I continued my look at the rifle by stripping it. Not too bad really but the spring guide was a pretty loose fit in the spring and the large circular end broken off. New guide is being made. Small O ring breech washer was somewhat damaged BS 010 seems to fit OK in the recess but I do not have the larger O ring. I think it is OK though. Mainspring seems fine... must measure it, as it the piston seal. I will also add a piston sleeve.
So next ... trigger reassembly. Why do I expect coffee to be in demand?

At least it is raining here so I would not be outside anyway.
Cheers, Phil

[evert]

Having stripped the relevant block out, I find a 2BA screw fits. Why a 2BA would not fit with the block assembled on the rifle in the first place I do not know.

Some Supersports/Lightnings I have worked on have had alignment problems with the holes in the rear block and the holes in the cylinder.

[Thegreg]

Some Supersports/Lightnings I have worked on have had alignment problems with the holes in the rear block and the holes in the cylinder.

The alignment issue is most likely caused by the opposing cap head screw which fastens through the Maxigrip rail, it makes the back block camber over when the rear guard screw is removed, sometimes chewing the thread too. A good tip to avoid this is remove both screws and reinstall simultaneously.

Cheers
Greg

[evert]

The alignment issue is most likely caused by the opposing cap head screw which fastens through the Maxigrip rail, it makes the back block camber over when the rear guard screw is removed, sometimes chewing the thread too. A good tip to avoid this is remove both screws and reinstall simultaneously.

Cheers
Greg

Yes, that helps on many guns. But a supersport I worked on recently had the hole in the rear block drilled out of center. My buddy was planning to make a scope mount stop, and use the top tube hole to fix the stop, thats when we noticed that there was no way you could enter screws from both sides at the same time.