Can it REALLY be that there's another Enfield forum circulating this planet? Really!
I think that the bloke who sent the 1949 trials stuff was our very own Nigel. I have to comment though that if there WAS a problem with slippery rings - if you'll excuse the phrase - I wonder why the same telescope carried on right up until the late 80's! And correcting those slippery(and defective as you'll read later, to boot) rings is simplicity itself. You can bet that as sure as little green apples, those protruding knobs would be the first thing that would get either a) broken off or b) moved around!
What you all probably don't know is that there is a +/- torque figure for the slipping rings. We use a SPANNER, torque, adaptor telescope and the little Armourers spring balance to measure it. Repair is by replacing the crushed double coil spring washers or shimming them up. The main problem is caused by well meaning amateurs greasing up the spring/centre spindle/thumbscrew with grease and this lessens the friction.
You could sum this up by saying that slippery rings are caused by too muchy grease! Ho ho ho...... Well it is a rainy Tuesday morning here in Oxfordshire
Back to serious though. Here's a thing you all ought to do NOW or PDQ if you shoot a No4T or an L42. When it is properly zeroed for YOU, count the number of clicks from the anti-clockwise end top to '0'. It'll be about 7 to 10 or so at a guess - maybe more or maybe less depending. Now do the same for the deflection drum. Now write this little number inside the end cap of the tele lens cap. That way, if you ever suspect that the slipping scale drum has slipped a bit during a shoot or while you are fumbling with the sight, during a rundown for example, you can always quickly check.
And yes, if you have these little undecipherable hyroglyphics wrtitten into the end caps, that's what they'll probably indicate. And if there is an 'A', that is azimuth which is the sniper term for deflection angles
There, sorry to go off at another tangent but there's another few bits of totally useless Enfield related info that you didn't know about