Having some trouble with zeroing my set up today. Popped the scope off and there are chunks coming out of the recoil lug of the back ring. Has anyone had this happen before? Scope was on there tight, but a heavy scope in a Vortex Razor 1-6.
I am sorry to hear this, but not altogether shocked. Do not despair, it has been seen before and it is all part of the really big thumpers world
Even drilled and tapped the receiver for larger screws on a second set of Talley mounts, locktighted and torqued the screws to 20 foot pounds. With light reloads, first round and the mounts and scope blew off.
I am on record for constantly telling first time DG rifles owners, again and again, to beware of screwed-on scope bases on heavy recoil rifles, and to prefer the CZ 550 double square bridge with integral dovetail to other rifles (e.g. Win 70) with screwed-on bases,
if only for this reason alone... Thank you Ridge Runner for sharing your experience, I can only wish that people who doubt that a scope can shear its bases would all read your post...
To address several posts in this thread, here is what I see here: clearly the surface coating chipped away,
but - from the picture available - it seems that the steel of the mount itself did not. It shows recess, but looking at the picture it does not seem to show a crack. This is important. Please read on...
Note: by the way, this is why one prefers traditional bluing, or modern plasma nitriding, to cera-coating etc. on mechanical parts. Coatings chip away, bluing or nitriding do not...
I have seen this before, and this is not necessarily terminal. What I have seen happen before is that the surface of the notch and the surface of the lug are not exactly parallel, so the edge of the notch progressively bites into the lug, and the lug gets mated to the notch until the two surfaces have full bearing, at which point the mating stops.
The bottom line is that the Lott and similar high recoil rifles (e.g .460 Wby; .500 Jeff, .505 Gibbs, etc.) are operating at the edge of mechanical survival for both mounts and scope internals. YES, lighter scopes help tremendously, but still, the forces at play are considerable... It is not by chance that in the old days .40+ rifles were not scoped...
Sure, tightening the rings helps - in my experience you should not be able to undo them by hand with simple thumb pressure. You want another 1/8 turn after maximum thumb pressure. I do this by laying a coin on the lever and pushing on the coin. The coin distribute the pressure of the push over its entire surface on my thumb, instead of the sharp lever end digging into it, and I gain substantially added tightness. It certainly helps.
Another thing I have seen bore and you want to check is that you want to verify that your front ring is far enough from the rounded end of the dovetail at the front of the front bridge, so that as the front ring moves forward while the rear ring seats, the front ring sharp edges do not dig into the dovetail rounded end. If it does, your point of impact will shift...
Yet another thing I have seen before regarding the Alaska Arms rings, I would advise against them on hard recoiling CZ 550. The recoil lug is not part of the mount itself, but it is part of moving clamp. This means that the brunt of the recoil forces are not born by the mount but by the screw. You can easily guess what will happen next...
In summary, I would advise to tighten the lever harder, per the method recommended above, and shoot another 20 rounds to see if things settle. I personally suspect that with the notch and lug surfaces in full contact, things will stabilize.
If not, then the hardening of the lug metal is faulty and there is nothing to do but change them...