New BCM with Troy Ind sights - Shoots Low No Matter What

AR/M4 AR Technical Discussion
1

I just bought a BCM Recce 16 and threw some Troy Ind BUIS on it. Sunday I took it to the range and tried to zero it and started off by shooting below the target at about ~25 yards. Then I cranked the front sight a couple of clicks and got it to hit the cardboard. A few more clicks improved it until finally I went to what felt like the front sight post was cranked all of the way down and still was still shooting 6-8" below the target.

This is my sight setup:
http://www.midwayusa.com/product/861762/troy-industries-rear-flip-up-battle-sight-di-optic-aperture-doa-ar-15-aluminum-flat-dark-earth
http://www.midwayusa.com/product/554172/troy-industries-front-flip-up-battle-sight-m4-style-ar-15-handguard-height-aluminum-flat-dark-earth

And a pic for clicks.

It seems I have the right sights for my setup, and I had 2 other people shoot the same target. They both experienced the same thing. :blink:

Help a new AR owner out?:cray:

2

The “up” direction will raise the POI; 1 click of elevation change is equal to 1 1/4" at 100 yards.

3

Yup… It’s cranked all of the way up, or clockwise (all of the way down) and I am still shooting groups super low.

4

Can you post pictures of your actual sights mounted onto your actual platform?

Do you have the right height sights matched up, and are they mounted properly in their “T-Marks”? When shooting/sighting in, are you using the smallest apperture with a solid rest or bench that is level with the target?

Which ammo are you using?

5

You appear to have your rear sight nearly over the ejection port.

Is there a reason for this? I believe this may be contributing to your issue.

6

It’s moved back now, it started in the last possible spot and then I moved it up to see if that solved the problem. It didn’t, so I moved it back yesterday and retried. Same issue.

Sent from my HTC ThunderBolt using Tapatalk

7

Try moving your target back to 50 yards and see if you can get it a little more refined.
Make sure you’re using the smaller peep.

8

Is your rail installed correctly?

9

Possible that the front sight post is too tall? You could always shave it down a bit if needed.

10

Place a straight edge across the entire length of the rail and upper receiver to see if you have a level platform for your sights.

11

Your rail may be canted slightly upwards. Is your barrel perfectly centered in the rail?

12

Beyond potential rail alignment, what are the odds that the installed post is the taller one meant for use in a F marked sight tower as opposed to a rifle sized post?

Granted, having to jack it all the way down does seem a bit excessive, but having the taller post wouldn’t help.

EDIT

Lemme correct that: not a post meant to be used in an F marked tower but the one used to compensate for the height difference in a rifle tower that’s mounted on a flat top carbine.

13

Just throwing out there… It’s not a front site for a gas block is it? Doesn’t seem to be from the pic but thought I’d ask.

14

At first I thought the same thing but it doesn’t have the circular ears on it.

15

Looking more at the photo I really think your rail is canted upwards. I had a similar issue with a Troy rail, although not as drastic (I was still able to get a 50 yard zero but the front sight was near bottomed out). Your barrel in the photo appears to be slightly towards the bottom of the rail. If this is the case this would mean your sight is positioned higher than it should be. I would attempt to re position your rail and see if that helps.

16

brizower,

Can you post a couple of close ups of the barrel location in relation to the rail from different angles?

That would help to tell if the rail is slightly off.

17

Just my $.02 here, but if it is indeed a “rail issue” as many are hoping to find here, did you purchase the rifle built this way? That is how I understood your initial post. If that is the case, I wouldn’t try to adjust it yourself unless you just really want to… Contact BCM and see what they think should be done. They may want you to ship it back to them for their own research/development team to look at, and should fix it if it is indeed their problem from assembly…

Just from personal experience, I bought a rifle with a Troy rail installed, and after I started shooting it, I realized that the rail was canted clockwise about 1/16th of an inch, throwing-off my POI on my iron sights… I took it back to the dealer and he had his smith take it apart and look at it. Wound-up being the barrel nut wasn’t properly tightened and when the FF rail was installed, it didn’t line-up with the upper receiver…

Take it for what it’s worth, but if it’s their product issue, I’d give them a fair chance to fix it…

~Bobby

18

Maybe take the bipods off and shoot off of a ruck. They might be putting pressure on the rail causing interference.

19

Thanks everyone for the replies.

Yes, I did buy the rifle complete.

I used my phone for pics because it was easiest.



It is hard to take a straight on pic of the barrel without it looks like it’s out of whack. But I did notice a step down from the reciever to the rail. I plan to call BCM in the morning to see what they recommend. It seems like the rail being out of whack is a promising lead though.

20

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Were you using the small aperture or the large?

Even though the group was not center, what was the best group you shot?

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