Have to re-zero every range trip

[EchoMirage]

i have a noveske chainsaw lower, and what i was told is a BCM upper with DD mid length barrel. i bought the upper used off this forum. optic is a new aimpoint PRO. ive found that i have to re-zero the gun nearly EVERY single time i shoot it. this last time, it was over 1.5ft left at 100yds, previously being zeroed dead on at 50yds. doesnt matter if it was a training day, or static 50/100yd range.

after shooting, all i do is clean it, and store it. it doesnt get knocked around, and the LaRue quick detach mount is solid and tight. the dot is screwed in tight to the mount. weird thing is, i had the same problem with a previous upper, and a different aimpoint.

the ammo can either be the exact same, or something different entirely, and i get the same results. im NOT that bad a shot, and it seems strange that with quality parts and sights, and the same ammo, its off by at least 18in at 100yrds. any ideas what it could be.

[3ACR_Scout]

Have you tried zeroing it with irons yet, to try to narrow the problem down to the rifle or the Aimpoint?

Dave

[223to45]

Barrel tight???

Aimpoint legit???

[Failure2Stop]

Are you cleaning your barrel after each firing session?

Sent from my VS980 4G using Tapatalk

[SpankMonkey]

Who installed the barrels? Are they on correctly?

Have you zeroed your irons?

[MegademiC]

Post a picture of your upper.
Check all screws and try rotating barrel, make sure everything is tight. Do you have irons? If not buy some. Zero the Irons and check. Try keeping the optic on the rifle between range sessions and see if its still off. If its the optic, you will see the dot float around in the sight picture. Is the muzzle device tight, straight and free of obstructions?

Either the sighting system is moving, the barrel is moving, or something is deflecting the bullet, or its you. What kind of groups do you get @ 100yds off a bench? Are you sighting in off a bench? How's the wind?

[Pappabear]

Zero with Irons , as has been said. You can start with irons or Red dot and then move accordingly. That should tell you a great deal. If you try everything and still can't fix it, me and Markm would be happy to go through it and test it out. You should be able to fix it your self though.

[markm]

Results this bad should be pretty easy to diagnose.

[EchoMirage]

i havent used the irons in a while, but they were zeroed at 50 and never touched. from what i remember, the irons held true. i just checked the co-witness now, and the dot is actually to the right of the irons....meaning to line them up, id have to move the dot even more left, which is opposite of what the target told me.

but regardless of that, i remember lining the dot up with the irons not too long ago. nothing was touched after....but now the dot is to the right of the irons, but still shooting a foot and a half left? and yet i had the SAME problem with a comp C3, and stag upper. halfway through a class, the dot moved in relation to both POI and irons.

its a real PRO, FSC brake, everything tight from what i see. it was off a bench, entire gun is always spotless, no wind.

[markm]

but now the dot is to the right of the irons, but still shooting a foot and a half left?

That MAKES SENSE!! If you hold the dot on your target, the irons are off to the left. Thus, the IRONS are correct and likely pointing where the bullet is impacting.... the dot needs to come to the irons position.

[Airhasz]

Op, have someone else shoot the gun and verify your findings.

[223to45]

i havent used the irons in a while, but they were zeroed at 50 and never touched. from what i remember, the irons held true. i just checked the co-witness now, and the dot is actually to the right of the irons....meaning to line them up, id have to move the dot even more left, which is opposite of what the target told me.

but regardless of that, i remember lining the dot up with the irons not too long ago. nothing was touched after....but now the dot is to the right of the irons, but still shooting a foot and a half left? and yet i had the SAME problem with a comp C3, and stag upper. halfway through a class, the dot moved in relation to both POI and irons.

its a real PRO, FSC brake, everything tight from what i see. it was off a bench, entire gun is always spotless, no wind.


So the same issue happened with a different upper and a different RDS???

[EchoMirage]

So the same issue happened with a different upper and a different RDS???

exactly. at that time, it was a stag upper, bushy lower, and comp C3. its now a nov lower, bcm/dd upper, and PRO. at least i was told it was a bcm/dd upper. the receiver is unmarked, and i havent found any "DD" markings on the barrel while looking through the handguard. at least i know its a real midwest rail, since its marked.

i know for a fact that the dot was centered on irons several weeks ago. nothing has been touched since, it was never banged around, etc. but now, the dot is significantly off to the right of the irons.

[Failure2Stop]

That MAKES SENSE!! If you hold the dot on your target, the irons are off to the left. Thus, the IRONS are correct and likely pointing where the bullet is impacting.... the dot needs to come to the irons position.

Yup.
If the dot drifts right in relation to the irons/impacts, then there is an issue with your optic/mount.

The common theme I am seeing here as a problem is attaching the optic to the mount and the mount to the gun.
LaRue throw-levers need to be TIGHT, as in it should not be a one-finger task to flip the lever loose. All of my LaRue mounts are tight enough that I need to pull the lever with my sling to detach the mount. What torque are you using to mount the optic to the mount. Lots of folks think that they are "tight enough" and are not, and a whole host of others are stripping out their threads trying to monkey the screws snug. A torque wrench is your best ally when it comes to optic mounting. Not using one opens up the possibility of variables, which is something that must be eliminated if you want to hold zero.

ETA; I am assuming that you are using the same ammo.

[EchoMirage]

the issue happened with all different ammo. ive noticed a different impact when trying different ammo before, but not 1.5 feet.

what torque is an aimpoint supposed to be installed. the lever is tight.

[TAZ]

Different uppers, different scopes but the same mount? Highly unlikely that you are unlucky enough to end up with 2 lemon uppers back to back. Are you sure the mount is good to go?

[EchoMirage]

its been a few years, but it was either a brand new mount, or another one i bought off of here

[TAZ]

What are the chances that you got 2 lemon uppers or 2 lemon aimpoints? If what you are stating is accurate the only constants in this equation are you and the mount. Check the mount to insure that the scope is in there snug and the screws are torqued and haven't loosened up. Then check the upper and mount interface. Can you release the lever on the LaRue easily. If so it's not tight enough. Mine are on there such that I have to exert some effort to close them and need something to leverage in getting them started when I try to remove the optic.

Have you tried the mount that came with the PRO justin case??

[EchoMirage]

both the lock and lever are tight. the rails are straight and clean. its not me....im not holding it so weird as to aim dead on yet hit over a foot left, and someone else shot 20rnds the same time, with the same effects. the screws are as tight as i can make them without stripping either the mount or the screws. does any know the torque spec for them? i doubt i have a torx socket that small anyway.

the only thing i havent changed is the mount. its a real larue cantilever. i havent tried the stock mount because i needed a cantilever for the magnifier. only thing i can do is after my house closes and ill be able to shoot off my deck, i can try swapping mounts. but it only seems to happen after sitting for a while. if i check the dot a few days after shooting, its still even with the irons.

[Thump_rrr]

both the lock and lever are tight. the rails are straight and clean. its not me....im not holding it so weird as to aim dead on yet hit over a foot left, and someone else shot 20rnds the same time, with the same effects. the screws are as tight as i can make them without stripping either the mount or the screws. does any know the torque spec for them? i doubt i have a torx socket that small anyway.

the only thing i havent changed is the mount. its a real larue cantilever. i havent tried the stock mount because i needed a cantilever for the magnifier. only thing i can do is after my house closes and ill be able to shoot off my deck, i can try swapping mounts. but it only seems to happen after sitting for a while. if i check the dot a few days after shooting, its still even with the irons.

I will repeat what others have said because I went through this with a friend 2 weeks ago at a CQB clinic.
He was having the same problem with an EOTech.
He said his mount was tight but when I pushed in the locking lever the arm had barely any tension on it.
In the case of the EOTech there is an adjustment screw on the opposite side of the lever which can increase or decrease the tension.

[rcoodyar15]

I have a larue SPR-15

my point of impact was moving. I thought I had it tight. I torqued it down and I mean torqued. Now the gun shoots half inch groups

I am still going to retire the larue and get a non removable mount for the scope.

[Scotter260]

Some years back this occurred to me with an M3 and an Aimpoint QRP mount. It seemed tight to the touch but still seemed to move on me. I got frustrated and tried more diligently to make it move in the mount, sure enough it would twist with more pressure. Apparently the recoil was enough to shift it in the mount while hand pressure wasn't unless excessively applied.

It did not shift that much but I'd find the dot in a slightly different orientation in relation to the irons every trip and then I'd have to move it back, would shoot another string and then the darn thing was off again.

[tog]

I had a similar problem once. Turned out the "problem" was a "buddy" who was trying to mess with me by moving my sights when my rifle was in the rack at the range.