Quote Originally Posted by Peter Laidlericon View Post
Going off at a tangent a bit - as we are want to do on this forum, the grat point of the No42 or 53 (I'm sure you meant the No42 instead of the big No22 sight Surpmil....) isn't necessarily centred in the tube as you'll see if you rotate a couple. This is because the grat or shooting line of the No 42/53 sight is adjustable on the gun frame to suit the BESA MG trajectory. These No42 and 53 sights are also a slightly larger diameter too, being 1.016(?) or so instead of 1.00". So you can use the tube to repair a No32 if you machine it down to the correct diameter. Which, most conveniently, just skims off the old No42/53 engraving too!
No, I was thinking of the No.22 Peter. Can't say how well centered they are on average, but the one I have is. Lots sticking out of either end of your rings makes them easy to turn.