Quick detach scope mounts

[Klem]

Max,

I agree with plumb-line levelling. SPUHR has something similar to the LEAP mount with an angled wedge coming in from the side to level the flat bottom of scopes when in the mount. I have found SPUHR wedge not to be as precise asan external plumb line. Maybe the LEAP does a better job with that flat-topped grub screw but there's still no guarantee the erector mechanism tracking is exactly true with the scope's base. And for that check you actually have to see how groups track on a Tall Target Test (TTT). I wasn't aware of the LEAP levelling screw and it looks pretty simple and smart (but still needs to be confirmed by a plumb annd then TTT. I agree, once levelled in the mount then it's levelled forever, regardless of the gun it goes on.

Maybe if Mark LaRue wasn't so proactive in denying his scopes to the rest of the world I'd still be using them; rather than SPUHR from Sweden. And maybe if SPUHR had brought out their QD earlier I'd be using them instead of their clamping screw model. But, I have evolved to using screws and find it pretty easy now to swap over in short order using a torque screwdriver; or in the field with a Torx key and torque marks. Unless you need to swap out scopes in an emergency (and I can't think of an 'emergency' where seconds count - immediately followed by a gun that now needs to be zeroed) then the ability to QD should not be the deal breaker - the quality of the mount should be.

[maximus83]

I wasn't aware of the LEAP levelling screw and it looks pretty simple and smart (but still needs to be confirmed by a plumb annd then TTT. I agree, once levelled in the mount then it's levelled forever, regardless of the gun it goes on.

Agree completely, whatever mechanism may exist in the mount for built-in levelling, you still have to confirm with external leveling system of some type (which often in practice is a real plumb line, or some improvised setup that simulates a plumb line). In fact, just a couple days ago I mounted yet another optic--a Nightforce NX8--in a Scalarworks Leap mount. Thought I used the built-in leveling screw initially, yet when I went through my usual process to check the reticle, it indeed was still not level. Remember that this is a Nightforce scope, sitting in a high quality mount. I think the underlying principle here is: regardless of optic manufacturer, you cannot rely on any approach to reticle leveling that uses the turrets or the body of the scope. Not even on a Nightforce! I've also leveled reticles on two quality Leupold scopes in the last couple months (a VX-6hd, and one of the older MK IV tactical models) which again, if you tried leveling them using the turrets, the reticle was not level. As good quality as the Scalarworks mounts are, the built-in reticle leveling screw still cannot be any better than the manufacturer; it relies on the sketchy assumption that the reticle is level if the scope body is level.

Bottom line: QD mounts, and Scalarworks mounts, are good. One big advantage of a QD mount is you get the reticle level once and it stays that way when you move between rifles. But for sure, don't totally trust any reticle leveling tool that relies on using the scope's turrets or scope body, the reticle needs to be compared to some external leveling device such as a plumb line.

[Wethepeople]

I don't expect a scope mounted on any mount to remain level when moved between rifles. QD mounts or other wise.
I run ADM and the Larue C.A.N. SPR mount on my ARs primarily for the convenience of tool less removal. RTZ in my experience is acceptable for GP use when removing and re-attaching the optic to the same rifle. Moving from rifle to rifle with the those mounts mentioned, I have experienced POI changes as large as 6" @ 100 yards. Many times, significant adjustment to the QD lever tension is required when doing so, which probably explains the POI shift. I have come to appreciate the tool less design of adjusting QD lever tension on the Larue mount and of course the cost. Ditto on plumbing to an external leveling source, always.

[Klem]

We,

You might be mistaking a shift in POI between guns with a shift in scope level. Once that scope is level in the mount, it is level for all rails. That said, if you take it off and on I have no doubt there will be a POI shift between guns, and even with the same gun.

To level a scope we do it on a rail. That rail needs to be level to the gound to avoid the gun being canted while levelling. So, we level the rail with a bubble and then level the scope somehow; using the base of the scope, or top of the turret, or eyeballing it, or using a downrange plumb line (best). Then test by shooting to make sure the plumbed reticle is square with the internal erector mechanism. To do this we Zero the gun. Then plumb a vertical line on a target: (1) fire a few rounds at the base of the line, then (2) dial it up 10Mils and fire again. Look to see whether the MPI of the two groups are in line with the vertical plumbed line.

Once you have done all this you know the scope is level with the rail. Taking it on and off any rail will be the same - the mount is now level with any rail it sits on. It doesn't matter if it is QD or screws, if you remove a scope from a gun while leaving it in the mount it will level for all guns. The POI shift you refer to is the vagaries of the permanent difference between the axis of a gun's rail and its barrel, made worse if there are different ambient conditions. In a good quality trued/blueprinted gun the barrel axis and its rail will be perfectly aligned, but they never are, especially when the barrel whips around while being fired. All guns are fdifferent in this respect and that's why you see the difference in MPI - and there's nothing you can do about it except re-zero.

[Kswhitetails]

Assuming the rails are all in-spec. I've seen out of spec rails which will accept the mount, but are rather obviously not square to the receiver. This would as Klem point's out, render the reticle no longer level and could cause problems at distance.

Wethepeople, I would be remiss to adjust the lever tension much. I have an FDE cerakoted upper that adds the thickness of the cerakote to it's outside dimension, which is the receiver I set the levers to. I have to man up to get them to lock on that upper. The rest are tight, but not gorilla tight. I don't mess with the lever tension, I fear that could indeed make POI shift more dramatic. If you have to really change that to get enough clamp between uppers, I'd suspect the rail requiring the most adjustment of being slightly oos. GL

[phishfood]

I ended up going with a Larue LT745. It is mounted on a rifle, and if this rain ever lets up, I will get out and shoot it.

[MoVal]

LaRue and move on

[Wethepeople]

Yes, I have an upper that requires the tension levers to be adjusted considerably to take out the wobble in the mount when moving it from another rifle. The POI shift is as described in my previous post. There is also a coating on the smaller upper. It's a blemished Vltor. It's the only upper I have that exhibits this large a change in POI and any mount I put on it needs adjusted tighter so it is an anomaly. Scope level does seem to change also when looking at a plum line. My solution was to run a dedicated scope/mount on this upper.

[Kswhitetails]

I think you found the "real" blem. An out of spec rail.