Jump to content
308AR.com Community
  • Visit Aero Precision
  • Visit Brownells
  • Visit EuroOptic
  • Visit Site
  • Visit Beachin Tactical
  • Visit Rainier Arms
  • Visit Ballistic Advantage
  • Visit Palmetto State Armory
  • Visit Cabelas
  • Visit Sportsmans Guide

BUIS alignment, and Red Dot QD issues-a 2fer


DNP

Recommended Posts

That's right, a 2fer. 2 issues in one topic.

Went up to shoot with my dad and my son today.  We were headed up to our usual spot on a buddies ranch.  Got almost all the way up to the meadow we like to shoot in and the road got a little too muddy.  Found a good spot, so we thought, to turn around and wound up stuck.  Took a little digging and a good tug from a Polaris ranger blocked of to a tree and we made it out of there...didn't get to shoot.  Took too much time unscrewing my situation.  We got back to my dads and set up on the 25yard range he has at his house.  Pushed back to 50 while trying to sight in his new aimpoint and his irons.  Ran into a couple issues that made that a mess too.

 

 

First up, anyone have issues having to run the windage adjustment completely to one side to get it aligned?  Magpul Pro on an upper straight from BCM. Whole upper came assembled by them, 14.5" mid length, pencil with pinned BCM comp and standard FSB. See photos.

 

Issue 2 : the QD on the aimpoint kept loosening. We'd shoot a few, make some adjustments, shoot a few more. Then all of the sudden we'd be all over the page again. Check the aimpoint, sure as poop...loose. We have the adjustment cranked down almost all the way. It's hard to work the cam lever almost. Don't know what brand the QD is. He bought the whole setup from CMC and I've suggested he give them a call tomorrow to ask. Take a look at the photos. I've never had a QD before, so I can say what's normal, but does this look right?  See how tight the gap is at the tightening screw. 

 

Being that hat we have two issues involving the rail on the BCM upper, could that be a source of our issues?  I've always thought they make a pretty decent product, but every so often anyone can make a dud. Could it be operator error, I will admit neither myself nor my dad are all that experienced with either of these items. 

image.jpeg

image.jpeg

image.jpeg

image.jpeg

image.jpeg

Link to comment
Share on other sites

At least Dylan had a good time at my dad's. He was pretty bored while we got the truck unstuck. He did have his own issues today though. First round he fired didn't sound right. Quite a different pop and lots of smoke from the action. "Ow, that hurt my ear". Even with plugs in, it hurt. "Something hit me in the face". He points to a couple spots. Looked like a little oil blew back. Not normal from a bolt gun. I popped it open and the whole bottom of the shell had blown off. I took it over, one round through it...no problem. Another round through it, POP!  Damn, that hurt my ear too. This one blew a section around the base out. We've run a box of this ammo before and it seemed like fun stuff. I only had two boxes from a day when that's all the local shop had in stock. He was nervous and didn't want to get back on the gun, but I ran about 10 rounds of CCI through it and showed him it's just that ammo. Might be a bad batch. He got back on and ran 50 through it. Then it was our turn to play. Still a good day with 3 generations together, but a day full of adventures. 

image.jpeg

image.jpeg

image.jpeg

Link to comment
Share on other sites

1 hour ago, DNP said:

First up, anyone have issues having to run the windage adjustment completely to one side to get it aligned?  Magpul Pro on an upper straight from BCM. Whole upper came assembled by them, 14.5" mid length, pencil with pinned BCM comp and standard FSB. See photos.

That rail is off - you can see it in this pic.  Left side is aligned based off the upper rail, but the right side is way off, based on the upper rail - it's not centered, and it's in such a way that it makes sense that the rear sight is cranked to the left to get it to shoot straight. 

That rail needs realigned with the upper, fo' sho.  Then it needs re-sighted. 

Check the pic, and you can see it now - left side edge straight, right side edge WAY off - that's enough to toss off that rear sight like it is...

 

Rail Off.jpeg

Edited by 98Z5V
Link to comment
Share on other sites

It'd have to be the tail on the upper. That's a fixed standard FSB up front. The HG might be a tweek off perfect, but plays no role in the sight picture. My thoughts were that the FSB might have been drilled a hair out of line and it could be twisted. That could be a cause of the alignment problem, no?  Either way, I may mail it back up to them to check out. 

Link to comment
Share on other sites

55 minutes ago, DNP said:

 My dad says he looked around online and found other people having the same issue. They were all on BCM uppers. 

^^^  That's the answer...

If the barrel isn't drilled right...

So, the barrel extension has to go on the barrel FIRST, because of the feed ramps in the barrel extension - they center everything. That thing gets torqued on at 175lb/ft, to the barrel.  THEN the extension (and feed ramps) are aligned, and that's the CENTER of the barrel, and the rest of the machining can take place.  After that, the gas port gets drilled ON CENTER with those...

It's not gonna be the MagPul rear sight that's off - but if it is, MagPul will want it back to check it out, and send you a new one before you even take that one off your rifle...

However, in that pic above, that rail is NOT centered on that upper receiver... Does the rail have alignment pins to center it? WITH the barrel nut?That can throw the whole thing off, right there...

Might be that all is machined right, but the barrel/barrel nut is not properly installed - torque dictates that if it's gonna be off, then it's gonna be off in the direction that HIS is off... I'm just sayin'... 

Look at it close...

 

Edited by 98Z5V
Link to comment
Share on other sites

I don't think I'm following. I'm slow. Will have to check back with you when I'm sober. This is the package we got from BCM. I keep feeling like you're talking about the DD Lite Rail. I'm pretty sure it can move to better align, but won't change the sight picture. I think the final answer will be a canted front sight the more I search the web, but I don't know. They claim they laser bore sight each upper they assemble. I highly doubt it's the Magpul and I'm fairly sure it shouldn't be the upper. The only other part it could be would be the Front sight. 

image.png

Link to comment
Share on other sites

4 minutes ago, sketch said:

Get one of those 3 way lasers from a hardware store and redline from front to back. I think survival shop has this process figured out if he chimes in? 

Your truck is stuck bro!

Good call. I have a decent laser at work. I can line that up I think. 

It was only a little stuck...just enough to cost us the couple hours we could be free. Had to meet a guy back at my dad's place at 11 so he could run a box of ammo through his pistol before he has to qual tomorrow. 

Link to comment
Share on other sites

18 hours ago, DNP said:

Checked into the mount for the aimpoint. It's an aimpoint LRP mount. May just need a lot of break in love. Tighten shoot 5-10 rounds, thighten again...we must have done that 5 times. Might have to buy him a Larue. 

Use an ADM mount for my Aimpoint and magnifier, never had an issue with it coming loose or not returning to zero.

Link to comment
Share on other sites

Yeah...Something not right there. No experience with the LRP but you don't need to break a mount in. It works or it doesn't. Is this one you can set the tension before you clamp it? It's possible to be too tight. You shouldn't need to crank it down to close the lever, the cam is suppose to do the work. Also are you pushing it forward hard into the slot while tightening it?

Edited by blue109
Link to comment
Share on other sites

Yep. Slid forward every time. Followed the instructions. Tighten a little at a time and test until it is snug enough that you can grab it and not shake it around. (Instructions mention if it becomes loose to repeat steps 1-4 for tightening). I would guess that you shouldn't have to do that more than one time. We had it shake loose 4-5 times before we called it quits. 

 

Got an email in to BCM today. We'll see what they say about the FSB.  Not going to worry too much about the mount. It may just need one more try. 

Link to comment
Share on other sites

Is the Barrel 1-7 twist rate ? Here is a Factory Colt Carbine I had to tweak the front sight a little to get it to be dead center , but it only helped a little , the Magpul rear sight is still over to the left a bunch , but not as much .

 Here is the Thread on the Colt , & man it was a lot of work to get everything aligned correctly .                   Factory Colt AR 15Carbine issue                 

Link to comment
Share on other sites

Thanks guys. I completely forgot about that thread, but I remember it now.  I asked BCM for their thoughts and recommendations for tests we can perform to rule stuff out. I will try a few different ammo combinations through it this weekend. After hearing/reading around the net...it's always the fully adjusted to the left side. That's gotta be from the sight post or the bullet twist with a weight the barrel doesn't like. Keep you posted. 

Link to comment
Share on other sites

My dissy/ASA upper has the armalite clamp on FSB. I laser borsighted it , and with the rear KAC sight dead center, but noticed later that the FSB was definitely canted a little. I got the FSB to where it looks perfectly centered and the rear sight is pushed pretty far right but the aimpoint lined up right with the front post. Both configurations were confirmed with 55gr ammo on paper at 50. Both worked at that distance. It really bugs me with the rear being off center, but the FSB was worse. I guess as long as it's zeroed I can live with it. 

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...