View Full Version : Zero shifted on my SCAR 17
Alaskapopo
05-15-13, 22:38
Went to check zero last week in prep for a LEO three gun match and my zero had moved 1 moa to the right and 2 moa down from when it was zeroed just 3 months back.
I am using a TR24 1-4 Accupoint in a Larue OBR mount.
Pat
steyrman13
05-15-13, 22:41
Has it been dropped or anything? Scope remounted?
I was just reading an old thread of you stating you never had re zero problems with larue mounts. I hope that's not the case
Alaskapopo
05-15-13, 22:48
Has it been dropped or anything? Scope remounted?
I was just reading an old thread of you stating you never had re zero problems with larue mounts. I hope that's not the case
Not sure what the problem is yet. I am using a 34 mm mount with spacers from Larue to make it work with a 30mm scope. That might be the issue. Have not dropped the rifle although it does ride in a case in my patrol vehicles trunk.
Pat
I had a number of similar, but more like .5 MOA, unexplained shifts with my Scar H.
Changed out the LaRue SPR mount to an ADM Delta mount last year and have not noticed any since. I have at least a half dozen range trips with the new setup.
Optic is a NF 2.5-10, which I do not remove when cleaning.
I've read reports of others with zero shifts when using magnified optics in LaRue mounts on the SCAR-17.
No personal experience, so take it for what it's worth.
Alaskapopo
05-16-13, 01:06
Thanks I was suspecting the mount might be the issue. Looks like I will be selling it soon and getting an ADM.
Pat
How much difference in weather between the two trips? Barometric pressure, humidity, and temp all change exterior ballistics.
Also, varying temp of the ammo itself will change muzzle velocities.
H
I would assume it is the mount.
C4
Barry in IN
05-16-13, 08:32
Probably an obvious question, but have you checked the barrel mounting screws for loosening?
The 17 really needs a rock solid mount.
I have an ADM Recon S which I used reversed (locking handles on the right, locking forward). I guess I had them a little loose or having them locked forward wasn't the proper thing to do (or a combination of both), because twice on two separate occasion the weapon rocked the locking levers loose, both of them. Thankfully the first time I was zeroing and noticed the shifts, the second I was doing close range drills and I was fortunate to catch the scope as I brought the rifle up from a low ready...
I've since flipped the locking levers to the rear and tightened the screw down one more notch and haven't had any issues since.
Just shows you that there is a lot of recoil action going on with the 17 and it's unforgiving of loose mounts / etc.
MadAngler1
05-16-13, 22:17
This pretty much confirms what I've read on the FN Forum, but with the Larue SPR mount rather than the OBR mount. I doubt the spacers help your cause any. I'm sort of surprised the OBR mount wouldn't work, since it's more or less the same layout as the ADM Delta mount, except it's thinner and lighter. I guess the rings and the levers really do need to be much more robust to handle the recoil impulse of the SCAR-H.
I will definitely be getting an ADM Delta mount for my SCAR, if I choose to go with a 30 mm 1-6x scope or a Short Dot. It's a shame they don't make a 34 mm version for those who want to run one of the new Leupolds.
http://www.midwestindustriesinc.com/index.cfm?fuseaction=category.display&category_ID=472
I wonder how well the VCOG will retain zero on the SCAR-H with its quick release Bobro mount. I only saw one lever in the ads rather than two. The thumb screw mount still has two screws.
Another source for the Delta mount:
http://www.primaryarms.com/American_Defense_AD_Delta_30mm_p/ad-delta-30.htm
It sits slightly lower than the LaRue SPR, but does clear the rear sight with the NSX and lens cap. Weight per my trigger pull scale is about 1 - 1.5 Oz more than the SPR mount.
http://i4.photobucket.com/albums/y141/shootist87122/SCAR17/Untitled.jpg (http://s4.photobucket.com/user/shootist87122/media/SCAR17/Untitled.jpg.html)
Voodoo_Man
05-17-13, 00:35
When's the last time you checked if the barrel nuts are torqued properly?
I'm sort of surprised the OBR mount wouldn't work, since it's more or less the same layout as the ADM Delta mount, except it's thinner and lighter.
The LT lever uses a spring to tension, so it never mechanically locks the mount on tight.
Interesting. I've been planning to get the Leupold Mk 6 1-6x20mm with the LaRue QD mount for my 17, having sold off the EOTech and magnifier.
The Larue QD mount I have on one of my ARs has always been rock solid, but that's not a 7.62. I wasn't planning on getting anything with an ADM latch, since I had an Vltor light mount with one, and it kept backing off under recoil on the SCAR, even after tightening it to the point that I was concerned I'd deform the rail.
One of the many reasons I ditched the EOTech 553 was the ARMS mounts that kept loosening under recoil...I'd hate to incur that on a more expensive optic and mount.
The LT lever uses a spring to tension, so it never mechanically locks the mount on tight.
If the spring tension exceeds the force that trying to open it that's not really true.
H
Try a SPUHR Mount.
"One man with courage makes a majority."
The design of the ADM mounts is brilliant. Not to knock Larue, but I dig how the ADM is more accommodating to out of spec rail sections
I would ditch the Larue mount immediately and get an ADM.
I have never had a problem with reversing levers on an ADM. They are suppose to be reversible by design. They also need to be tight enough that they hurt your fingers to lock them and you need a strap to open them.
FlyingHunter
05-20-13, 20:30
Had good luck so far running ADM reversed on my SCAR 17
I have never had a problem with reversing levers on an ADM. They are suppose to be reversible by design. They also need to be tight enough that they hurt your fingers to lock them and you need a strap to open them.
Yeah, I believe that I simply didn't have mine tight enough. I mean, they were tight as hell, but now they are a notch tighter. I just reversed them so they all close to the rear for simplicity sake, not just the mount on my 17, but others too.
Still it was interesting that just being a little looser, with absolutely no play in them that the 17 rocked both QDs open twice. I hadn't taken the scope / mount off, none of that. And honestly if it didn't happen to me I probably wouldn't believe it.
Regardless, I tighten the screws down one more turn now and still use all ADM mounts as QDs.
steyrman13
05-31-13, 11:42
After reading this thread and others. I decided to try out the Bobro QD mount. It is the 34mm edition. This thing is a beast. It adds ALOT of weight. My Bushnell HDMR with it feels like it weighs twice as much as a Leupy Mark 4 with Larue mount. If it maintains Zero POI shift from dismounting and moving across platforms, I will be ok with the extra weight. Although the reports of Larue and ADm are less than 1/2 MOA shift from remounting so The weight may not matter that much to many.
DiabhailGadhar
06-08-13, 11:41
I just bought a larue SPR mount for my scar 17, after reading this are you guys saying I'm going to run into issues with this mount/rifle combo? If so what are the steps necessary to prevent this or did I just get a $200 rifle mount that isn't going to serve me well?
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