Return to Zero?

[mikebravo]

I recently purchased a RRA High Rise mount to put a Pentax 3-9x40 Gameseeker II (Cheap scope, but not all that bad) on my M&P 15. I took it out today to get it zeroed, and was soon shooting raged-hole groups at about 75 yards. Took it off to play around with my Vortex SPARC, then put it back on to finish the day. Only problem was that the zero was off by about 3-6 inches. I really can't have this, because I'm going to be switching between optics a lot. Are there any good RTD mounts out there for a decent price, or do I have to cowboy up and drop $200 on a Larue? Attached are pics of my rifle in each configuration.

 

[Carne Frio]

Maybe a better mount ?
http://www.bravocompanyusa.com/SearchResults.asp?mfg=LaRue+Tactical

 

[jmr40]

I've never had a problem switching back and forth on many different guns, not just AR's. Are you sure you put it back into the same slots in the rail. 6-8" seems almost impossible otherwise.

 

[mikebravo]

Just for clarification, I did make sure to use the same slots. (And it was more like 3-6")

 

[TonyAngel]

Your results are not that unusual. To get the most consistency, you need to use both the same slots on the rail AND the same amount of torque on the screws. A pretty easy way to do this is to just tighten the screws and then use a paint pen or something to mark the position of the screws. This should get you pretty darned close.

Otherwise, look at Larue, ADM (American Defense) and Bobro; all of which are mounts designed for your intended purpose. I prefer ADM mounts and have been using them for a good while. As of the last time I purchased one, Smartgunner had the best prices on them, by way of gunbroker.

 

[nipprdog]

Cheap scope, yep.)

$70.

So you spent over $100 more on your red dot, than your scope????

Seriously??????

Btw, I'm planning on picking up a Sparc.

 

[10-96]

I didn't have that mount, but I did have similar issues. What cured mine was to push out the cross pins, and GENTLY run a small flat mill file across all the flat areas on the inside of the mount.

What I'm thinking is 1. they didn't clean up the machining burrs as well as they could have. And 2. When the harder steel cross pins are seated and/or pulled too tight- it can cause puckering of the softer aluminum thus giving you a slightly different seating position depending on whether the cross bolts are snug to the front of the slot or snug to the rear of the slots.

A small flat file will tell you if you have any high spots on the inside flat contact areas. Other than that, unless there is something seriously boogered with the scope- it should re-mount absolutely the same if there is no adverse influence or floposis from the mount.

 

[jmr40]

FWIW, I simply bought this.

http://yhm.net/index.php?main_page=product_info&cPath=2_8&products_id=130

and used Weaver rings I already had.

I have 3 AR's with several options for optics and iron sights all pre-zeroed. I simply use a multi-tool, or screwdriver to remove the Weaver rings and swap around all the time. Have done the same for years with other rifles and have never noticed a shift in zero when returning a scope back onto a rifle.

 

[mikebravo]

nipprdog: Yep, I was planning on saving up for a better one, but it was on sale, so I couldn't resist. The SPARC is a great optic!

 

[madcratebuilder]

When you install the scope on the rail you need to push it forward, against the rail slot, as you tighten the mount screws. This well help to a degree. I am generally within a moa when I R&R scopes. I use Warne QD steel rings. Bring the screws lightly snug, then tighten the rear screw first.

Tighten the front or rear first is not that important, doing it the same way each time is.

 

[taliv]

or do I have to cowboy up and drop $200 on a Larue?

hate to say this but larue is sort of on the low end these days. it works and is reliable but there are better and much more expensive products out there.

compare the mechanism on these to larue
http://www.gdiengineering.com/store/products.html

 

[Gtimothy]

I have a Leupold Mark AR duplex scope mounted in one of these and have not had any issues with losing Zero. I remove my scope after shooting so it doesn't get banged up. A bit pricy but I'm VERY happy with it!

With quick-release mounts, the trick is to get it properly adjusted and sighted in then use the provided lock-tite on the quick release nuts. Takes all of the guess work out of torquing things to a "mark" on a mount.



http://www.americandefensemanufacturing.com/view/product/8/

 

[Micro]

Burris PEPR quick detachable. IMO, one of the best of its kind at any price.

I know LaRue is very fasionable. But IMO, its individual vertical locking mechanisms are weaker than a single horizontally drawn clamp. And I've seen several rifles that have rails that are significantly scarred from the LaRue clamps.

 

[wally]

I've got a pair of UTG QD rings on my Trijicon Accupoint on my RFB, The RFB has been back to the factory three times sans scope and I haven't messed with the scope settings since the initial zero.

Any zero shift is less than the POA/POI variations among the various ammo I've been trying in an attempt to make the darn thing decently reliable.

Inexpensive doesn't always equal poorly made.