Range report, LWRC SPR/DMR. Need help/input.

[Snake Plissken]

Here's the rifle:

LWRC SPR body & gas piston system, 18" DMR barrel. Trijicon TA-31F ACOG. Magpul MOE fixed stock, MIAD grip, RVG. Setup meant as an LWRC SDM-R/SAM-R/M16A4.

Here's what happened today:

Weather was humid/cloudy/scattered drizzle rain.

The first 100 rounds or so the thing was grouping decently at 100 yards. Made a few click adjustments and the whole thing went pear shaped. Wide groups, if you could even call em that. Consistently inconsistent.

My buddy and I both tried to see if it was a shooter error on my part. We both had the same experience.

Yet it shot fine at 50 yards! Once we checked that and tried again at 100, we got a so/so group out of it.

We figured, it's one of those days, we've all had that experience where a rifle won't cooperate and you're rushing shots out of frustration, only to try again a few days later and find it works fine and there's no issue.

I wanted to say it was a trigger issue because it has the EFCG, but I couldn't dupe myself into believing that since my 14.7" M6A2 has the same FCG and groups fine at 100 yards when I check zero on the EOtech 555.

Damn waste of ammo

Ammo used was Federal XM193. The thing grouped beautifully with its iron sights, and when I zeroed my Leupold Mk. 4 3.5-10x40 on it with the same ammo last time I had it at the range, a good few weeks before the MOE stock shipped. Hence my confusion and frustration over the matter.

What could the problem be? One of those days? Throwing the shots? I'm stumped.

 

[SJshooter]

Re: Range report, LWRC SPR/DMR. Need help/input.

Sounds like it could be parallax error. Did you adjust correctly from 50 to 100yds? I've made the same mistake before.

 

[Snake Plissken]

Re: Range report, LWRC SPR/DMR. Need help/input.

We just figured, after getting stumped over the wide open groups at 100, that we'd make it easier on ourselves by shooting at 50 to make it easier to track on paper and make groups, and then adjust for elevation at 100 once that was dialed in.

So we went from 100, to 50, back to 100. No adjustments made.

I didn't know you could have a parallax error on a fixed magnification optic with controls only to adjust windage and elevation. Elaborate please?

 

[hewlett260]

Re: Range report, LWRC SPR/DMR. Need help/input.

Did you tape the fiber-optic to dull down the reticle? Also which reticle do you have? something to keep in mind the ACOG wasn't meant for shooting tiny groups, it was meant for a compromise between working well in low light, medium to fast target acquisition, and engaging man size targets with the M16/M4 platform out to the max effective range of the weapon system (between 500 and 800 meters depending on which military pub you read) and be durable enough to take the abuse of being in combat. With that in mind, if you want tiny groups go back to your Mk 4. Last thought did you check the screws that hold the ACOG to its mount?

 

[Snake Plissken]

Re: Range report, LWRC SPR/DMR. Need help/input.

Yes, I put a strip of duct tape on the fiber optic tube to dim/sharpen the reticle. Reticle is the chevron.

I wasn't trying to shoot clover leaf groups. Here's an example of what I was trying to accomplish at 100 yards:

Not this:

Know what I mean? It's a combat optic, I want combat accuracy out of it. My EOtechs and Elcan can do it, I want this one to do it.

The thumb screws were/are tight to the point that I can't tighten them any further.

 

[Snake Plissken]

Re: Range report, LWRC SPR/DMR. Need help/input.

Turns out you gotta tap the adjustment knobs every time you make an adjustment. It's even in the FM on zeroing optics @_@

 

[Snake Plissken]

Re: Range report, LWRC SPR/DMR. Need help/input.

Doubletap