Repro no 32 mk ii sight problem

[jr57]

Yes this is a Mk 2 variant from Numrich. I certainly didn't overtighten the lock rings and just followed the instructions in your book. The were left finger tight initially. I had a collimator fitted at the time and noted the settings for future reference. I tightened the rings just a bit to make sure everything was secure and checked the collimator to see if the reticle had shifted which it had and thats when I discovered the problem when I tried to adjust the elevation. there was

I have never had one of these things apart but I knew that Warren on this forum has had dealings so maybe he'll come in here.

BUT, if you have no range adjustment, it seems to me as if the lead screw nut part of the diaphragm assembly has unscrewed from the leadscrew.
As for the drums locking up when you clamp-up the lock rings (can I assume that you mean the lead screw locking rings as it's a Mk2 variant?), well, I might sound a bit glib here, but my advice has always been - well don't do the buggers up tight then! If you are well forwards on the advance into Antwerp in 1944, then tight is fair enough but if you are shooting at targets for fun on a well manicured range on Salisbury Plain in 2012, then your lead screw clamping nuts only have to be tight enough to lock the lead screw. Nothing more nor less. I have seen them tightened down like Jumbo jet wheel nuts

[Warren]

Nothing wrong with the tube diameter and the cradles.....the problem is the slot in the front of the mount for the aligning pin on the scope. Most slots on the mounts are undersize and I have had to run a milling cutter or use a dremel tool to open up a number of the slots. The axial alignment of the rings appears good on the repro mounts I have checked with a mandrel, however again...on the majority of the mounts, the slot is just too small for the pin.
I've attached three pictures showing:
3- degree which the scope does not fit when the aligning slot is undersize (the marks on the tube were caused by "buddy" forcing it )..... This is one that had the turret broken loose.
2- marks on the tube caused by forcing the pin into the slot
1- ditto
sorry on the listing of 3,2,1,...it was easier than rearranging the photo's. I've done well just getting the photo's here ... :-)##

[Peter Laidler]

Yep, I see now. Thanks for that Warren and others. Forewarned is fore-armed as they say. Warren will probably agree with me here but working on a bracket is a sod of a job because the part you want to get to, the cradles and threads - or in this case, the anti-rotation slot, are the hold-ontoable parts!!!!! When I had about 70 or so virtually corroded to scrap brackets to do I used a scrap No4T body and mounted the brackets onto the body which was mounted into a milling machine/drill press. That was the only way I could get a secure and more importantly, square hold!

[jmoore]

Surely, if the geometry of the 8x taper lock cradle cap clamping screws and corresponding holes in the caps is correct,

Which isn't the case with the reproduction brackets. The screws on these (most of 'em) are of the non tapered head variety. Regular old flat bottomed heads.

[Warren]

Attachment 36131Attachment 36132All the mounts that I've seen and worked on have the tapered cradle screws, and the last lot I got were an excellent copy of the REL mount.
The only difference in the screws are the repro screws are SAE thread while the originals are BA.
I've also attached a photo of the offending slot in ALL the repro mounts. The aligning slot is just cast and not machined so the spec's are not exact and most slots are undersize. This has been causing the problem with breaking the turret body loose when the scope is forced into mount, as per my previous post.

[jmoore]

I'll check the one on hand, but there are some of the cheapie brackets that have the non-angled screw heads. But those were seen near on ten years ago. Haven't checked the current crop.

[jimmieZ]

I have a repro bracket from Sarco - it has the angled screw bodies. The only fault I found was the screw heads "stood proud" above the clamps when fully tightened. I managed to find some fairly reasonable diamond dust grinding burrs for the Dremel. I carefully worked the tapered holes in the clamps to a wider profile while maintaining a correct angle. The result is screw heads level with the flange on the clamp (no longer standing proud of the clamp). Looks much better. Still not as good as a real bracket, but not as ugly as before.

Jim

[Surpmil]

It would appear that the ring caps are cast separately, rather than in one piece with the bracket then cut off as per the originals. The shoulder details don't match.