No1Mk111 Receiver Holding Fixture

[Surpmil]

Can the accuracy and parallelism of the jigs, or the mounts be relied upon to the extent that if the locating of the machined bearing surfaces on the body is identical, the collimation of the centers of axis of the rings and the bore will be perfect when fitted up?

Maybe it is possible to achieve that level of accuracy, but only with perfect collimation of the jigs to the bore. Not an easy thing to achieve, though H&H apparently did, or close to it. But then they weren't rotating the body and they were using rifles selected for accuracy so the variables such as the squareness of the boltway, barrel threads and front face of the body could be assumed to be satisfactory. But when using unknown barrels and bodies, is it wise to assume that? Granted that Lithgow made the best SMLEs.

I can't see anything beating lasers, or a boresight in the chamber and a plain telescope in the rings for accuracy, since the collimation can be checked over 50 or feet or so against an aiming board marked to reflect the center to center distance of the rings and bore. The No.22 scope is a cheap, readily available and has a plain reticule, presumably optically centered from new, since there is no provision for internal adjustment.

Having the rings securely clamped around the body of the No.22, after the alignment of the reticule to the outside of the tube and the parallelism of the tube OD has been confirmed, might be the easiest way to ensure that when the solder on the bases cools everything is in the right place. One of those Soviet or East German boresights sometimes seen on ePay with an adaptor made to fit the chamber might be better than just a new .303 case with a hole through the primer recess.

What the built in angle of deflection was I have no idea, but no doubt you do. Tricky to get the crossbar in the front base exactly horizontal. Is there any reference except the foresight if none of the external body surfaces are reliable controls?

Probably they did most of the collimation when setting up the rear base originally? Would be handy if you could attach the front base with a single screw first to allow just a hair of rotation if required before soldering and screwing down? It's that or file out the back of the 'hook' on the front ring for whichever side is required, but no going back once that is done!

One of those odd instances where the old ways are still the best ways?