The very scope that slipped in the rings, I took it off at some point later after I torqued the hell out if it because it slipped. The tube was like you say slightly smaller having been squeezed under the rings. No affect to the scope, but you could feel at the edges of where the rings were that it was crushed some.
That was taken into consideration when I used the Ruger rings and later the Burris insert rings on my Ruger 416wby with the 3.5-10 Leopold. I tightened tham just as tight on the Ruger rings. When I removed it to use the Burris set for more elevation offset, there was absolutly no marks or crushing at all. I figured it would. I was expecting it might try to move in the rings so it was tightend hard as well. Later I went from 30 moa inserts to 40 moa and noticed when I had the scope off the Burris rings had not squeezed the tube either. I don't know if this is indicitive of how thick the tubes are comparing Leopold and Nikon, just my experience.
I agree that the clamping force is due to bolt stretch not the friction between the threads and the head. If you over stretch them or stretch them too many times (3 times max IMHO) they will loose their tension. Many bolts actually create more clamping force when stretched to the same length the second time than they do the first. On the third it just about equals the first and goes on a downward trend steeply on or after the fourth retorque. This is true for a pistons connecting rod bolts I know for sure.
As scientific or methodical as I usally am about these type things, I still prefer and trust my "feel" for the torque on most bolts or screws. I do however use a torque wrench for rods, mains, head bolts and a few other things of extra critical natures. [img]images/icons/smile.gif[/img]
I once saw several 3.5-10x40 1" Leupold variables that had all been overtightened, causing a very obvious ring indentation, to the eye and that could be felt when you touched the tube. Another time I put a brand new Burris Black Diamond into Burris rings and torqued the capscrews and managed to make a pinch type mark where the ring halves came together. That really pissed me off because the tension was only 15 inch-pouinds and still the rings dinged the scope body. Cosmetic only but still there (this was not the style with the plastic insert).
I find these matte finished scopes much easier to mark, particularly at the join area where the rings should come together. Some rings are just too sharp cornered, they scratch too easily. That is one real benefit of the plastic inserts as in the Burris's, Sako's etc.
Interesting comments on the screws/bolts stretching - all the more reason to use a torque screwdriver or wrench.
Also I guess this is why I like Badgers, never heard of a scope slipping in those suckers.
When mounting the rings (nightforce) on a one piece mil-std-1913 base. before tighening there is play in the ring to base slot (forward and back). do you guys but both rings to the back of the slot, both rings to the front, back to front front to back, or front to front and back to back? Do you keep the rings as far apart as possible?
When we install the rings onto the Picatinny style bases such as Badgers or Nears we always push each ring forward, as in towards the muzzle and lock it with the 1/2" socket. Then I use the 65 inch-pound Seekonk snap-wrench on the nut. Idea is that recoil forces backward are best handled by having the rings tight to the ring slot in the direction that the forces are coming from.
Have never tried any of the other combinations, perhaps there is some merit to another method, but full forward has worked very well on a large number of rifles.
S1 just used the dreaded term "lapped" - perhaps he could suggest a good procedure for lapping rings. I have done the procedure several times with MK4's and was surprised at how much polishing and metal removal took place. Have never lapped with Badgers. I am too dense to understand how the top portion or shell of a ring does not have a significant input in fitting the scope to the rifle - I have been told that it is the equivalent to steel "duct-tape" and that only the bottom shell has to be lapped.
I will push both rings forward and torque.
Before lapping I was told to tighten the rings onto the lapping bar and touque them down. Disassemble and lap the bottom rings, and assemble with scope.
This sounds like a resonable way to check every thing out and not smash the scope.
I have always pushed my rings forward too for the reason you stated.
The reason the bottom only needs to be lapped in my experience, is that when the rings are torqued to the bases, as you know the scope will not make even contact with the lower halves even with the slightest misalignment. The tops halves simply follow or float on the scope tube, aligning themselves with the tube until, and "if" they make contact with the edges of the lower half, at which point they will "then" distort the tube. I've only seen that on Ruger rings, as they come awfull cose to contacting each other even before lapping. Be carefull to keep clearance on each side equal and it usually won't happen.
I never tighten them on the bar first for this reason. The rings will not set in their natural position and be lifted up in the front or rear as they are torqued to the bar, so when they are tightened to the bases it will now not even need lapping because it is already in alignment with the tube, or really, really close. I see the purpose of lapping to do just the opposite, to seat them naturally, up forward and tight where they want to set. After that, lapping aligns the bottoms, placing no stress on the tube.
Hope that helps. [img]images/icons/smile.gif[/img]