Quite right, and thanks for that.
I said:
'...and taking a very high grip screwdriver I forced a small amout of extra hard tightening up of the screw'
That is; 'a small amount'., and as said maybe even a little less than a quarter of a turn, that would probably never strip any thread coz I don't recomment OVER tightening, just a nip up...
With caution it can't do any harm and believe me when I say that I myself really did nip the screw up VERY tight - maybe a good half at least or more of a turn and without the thread stripping, and I say just use your intuition and if you should strip the thread (Very unlikely imo) then nothing ventured nothing gained when the leaking mag is scrap anyway.
If I was a Barrister, erm, I would say 'I rest my case', LOL.
Cheers all, don't take all such stuff too literally, chill....
FINAL COMMENT: If the mag is leaking then its scrap, so worth a try, and as said, it really did work for me.
Don't shoot the messenger mates.
I totally agree when you say, quote:
'Better to take the mag apart and apply silicone grease/oil to the seal (square o-ring) and valve rings.
Do it right, do it once. And it takes 5 minutes.
There are other, more invasive, permanent fixes like sealing the base shut with silicone but they are a last resort kind of operation. To try when the only alternative left is to bin the whole mag'.
But I say again, nipping up the screw a bit is worth a try...