Installing the rings

[mike452]

I was installing a set of rings on the scope rail and this same question came up again.

Do I put the cross bolt on the rings against the back of a rail slot or in front of one?

I installed them touching the back of the rail slots thinking the recoil will kick the rifle back making the scope/rings going forward. Is this right? It's 2am. :confused:

[Technical Ted]

Against the front.

[rkt88edmo]

When you shoot the recoil impulse is pushing the rifle backwards while inertia is keeping the scope in place. So the scope wants to slide forwards.

[donger]

Man look at the time stamp of your responses.

When do you guys sleep?

[xenophobe]

Umm... if your rings slide back and fourth when they're attached to your rail, that means you bought Weaver rings and have a M1913 rail.

Do yourself a favor and buy some M1913 rings.

[mike452]

Xenophobe, I think you are wrong on this.

I am using M1913 rings and rail. It's a set of Nightforce rings on a Near 20MOA base on a FN SPR.
I also tried everything I owned including Badger rings, Warne rail, TPS rings, Mark 4 rings, and Armalite 1 piece rings. The only thing that fitted perfectly and didn't move was the Armalite 1 piece ring/mount. All the other cross bars were narrower than the M1913 rail gaps.

[maxicon]

This is pretty common, I find. I've measured a bunch of mounts and rings, and find that few of them closely match the slot size in the Picatinny/M1913 spec. The majority of rings have recoil lugs or cross-slot bars/screws that are narrower than the Picatinny spec slots, possibly to provide compatability with non-spec rails.

Warne Maxima have a pretty skinny removable recoil lug, my ARMS gear has square shafts on the cross-slot screws that are narrower than the slot, and my Eotech uses the cross-slot screw for a recoil lug.

The Armalite one-piece has a recoil lug molded in as part of the body, and it's pretty close to the slot width, but I don't have the measurements in front of me. Likewise, my YHM flip-up sights are also very close, such that the fronts won't fit in a railed gas block I have that's a bit narrower than Picatinny spec.

I don't have any high-end gear like LaRue, so haven't made the measurements on them.

It's unfortunate that most vendors don't supply detailed dimensional data on their optics gear. It would save a lot of the hit-and-miss fitting you see out there.