BSA Supersport head scratcher

[WebleyWombler]

It's the same size as the thread for the front sight if that helps.

I have a trio of Superstars and the sights are held on with M3.5 screws. Try taking a fixing screw out of a 240v 3 pin socket face or a lightswitch and see if that fits.

[evert]

I have a trio of Superstars and the sights are held on with M3.5 screws. Try taking a fixing screw out of a 240v 3 pin socket face or a lightswitch and see if that fits.

Are you sure they are M3.5? I have always thought they were 4BA? But M3.5 is very close in size to 4BA, so that may be the correct size.

[angrybear]

Size wise 3BA is close, but the BA thread is way too fine,
nothing on my metric thread gauge was an exact match, 0.5 & 0.6 were close but the angle isn't quite right, which is why I guess 1/8 unf.

Edit; I stand corrected under a magnifying glass it is indeed 4BA, but the thread is still too fine to fit my Supersport

[WebleyWombler]

Are you sure they are M3.5? I have always thought they were 4BA? But M3.5 is very close in size to 4BA, so that may be the correct size.

Your thoughts are correct sir! 4ba is a much better fit than M3.5. I've always used 4ba on Webley Hurricane sights and have just tried a Tracker and that is the same as are my Superstars and a couple of meteors.

4ba does seem a common size on classic British airguns