Fitting a Scope and sling on a 4T

[snipershot1944]

How much are copies of the No 32 booklet Brian?

[Brian Dick]

The price has increased to $20 per copy plus shipping of course.

[Peter Laidler]

Good observation JM> I know exactly what you're saying about boring/drilling through a threaded hole JM - and it's true. But the few .001" or so that the bore might be 'off' is easily catered for by a very slight adjustment in the slipping scale and the fact that the shaft of the rear thumbscrew is quite loose in the bracket. All that screw does is to pull the bracket down on a linear dovetail.

[ArtioZen]

As per the procedure for tightening the front scope mount screw first and the rear last, this may relate to the standards of precision machine fixtures - where for an age the best practice multi-axis alignment hardware feature a “cylinder" and "diamond" location / lock feature for X and Y directions – they too are tightened cylinder first and then diamond.

In the case of the No4t the “cylinder” is the front mount screw position - actually used to load the end surfaces of the male and female cylinders into contact within the bracket and mount to establish the collimation of tube over barrel - X control - it can also act as a pivot point still around the axis of the cylinders.

The rear mount screw position feature the a rudimentary “diamond” geometry - the corner of the "diamond" being the male bracket features into the female vee-slot rear mount - tightening the rear mount screw last will the cause the vee faces to want to achieve even surface pressures from any alignment mismatch and will manifest as leverage acting around the front mount cylinders (pivot) to correct the Y alignment (achieve elevation zero)

So if you tighten the rear screw first you lock the elevation and then the front mount screw can only draw tight and not provide any pivot action - this way you risk losing a handful of millionths of elevation correction (0.0001" error approx .1 MOA) - Dirt, goo or sticky body fluids on these mount surfaces would also add to the error – play clean!

Also the same mechanics observed for building a function replica – front pad first – collimate the tube / barrel axles, then set the rear pad for elevation. I don’t mess with scopes much, but I would expect other mounting systems to work (best) the same way – get collimation first and then elevation…

I am prepared for minimal praise and maximum rollocking sir(s)!

[Surpmil]

FYI: The "No.4T An Armourer's Perspective" by Laidler/Skennerton is now out of print and sadly, there's no plan for more.

What about an "e-book" in that case? Or a DVD for that matter?

[Brian Dick]

Ian Skennerton would have to make those decisions since he has the publishing rights. He still has some copies but you have to email him directly and they aren't $30 anymore.

I'm hoping Peter and Roger join forces and write a new one since we've all learned so much since the early 1990's. Hell, we're still learning!