Received my BCM 16" middy upper yesterday, but I can't line it up completely with the pivot pin holes in my spikes St-15 lower. The best I can get is that the upper is about 1/16" short of lining up perfectly. Not sure if the upper's DD Omega rail is preventing it from moving further back or the "ears" on the lower's pivot pin hole are too large.
Yeah, its my first build (my first AR), so be easy on me. Suggestions are welcomed!


 

pictures?

good point. I'll take some photos tonight and upload when I get home.

Put the front pivot pin in first, put the buttstock between your legs and pull the upper down while pushing in the rear pivot pin.

Is it closing completely?

I found on a tight fit with a rock river lower and another mfg upper is that pulling the hammer back can help.

Good luck - can be a royal pain in the ass...been there - and did not enjoy that trip.

I ended up just just using a rock river upper / lower combo - it was a tight fit - but it worked out well.

Brad

that's the problem......it won't line-up with the front pivot pin holes. Working on posting pics..........













 Brad, was this to get it on the front pivot pin, or were you "rocking" it into the rear takedown pin? I'm beginning to wonder if I should go buy a bcm lower instead.





 

 

+1 Spike's Tactical for Bada$$ customer service

I think I have a similar issue on my LaRue Stealth Upper and Lower.  It takes a lot of time to get the front pivot pin through the lower just because the machining tolerances are so tight.  So, its not actually a problem it just takes a little extra time, but fits together flawlessly once the pin is in.  Is that what is happening to you or is there a physical obstruction or something?

In for results i have the bcm middy upper and was planning on purchasing a spikes lower can you tell me what Gen your lower is?

Since this your first AR, do you have a buddy that has one you can try fitting the upper to? Casting no dispersions on STas they'll jump to make it right, I doubt seriously the BCM upper is off spec.

. Not sure if the upper's DD Omega rail is preventing it from moving further back



^^^^^^^^^^^   Unscrew and move the rail further toward the muzzle and see if this is the problem

Instead of trying to get the front pivot pin in first try setting the upper flat on the lower and align the two pin holes the best you can and squeeze them together ..  try pushing in the rear taken down pin first ... then see if the front pivot pin will slide in.

is the the hammer cocked back?

Ok, you keep saying that something is preventing it from moving back farther.  Are you setting the entire upper into the lower and then trying to line up both pins at the same time?  If so, what you're supposed to do is the line up the front pivot pin first.  In other words, don't set the whole upper into the lower.  Have the upper at an angle to the lower and line up the front pin, then swing the upper down into the lower.  Some matings take a little coaxing.  The trick is to know how much is too much and being new, you won't know.  You should seek help if coaxing is required.

I had something similar happen when I rebuilt my upper with a BCM receiver and put it on a RRA lower.  On mine, I got the front pivot pin in and when I went to swing the upper down into the lower, it would not go.  I slid the upper into the lower, into somewhat of a situation that is being described here and GENTLY mortared the butt on the ground.  It slid in and after the first time I shot it, all was fine.  There was no loss of anodizing or anything.  It just took a little coaxing.

If you have a situation where the upper is sitting in the lower as it should be when assembled and you have the rear pin pushed in, but the front pin won't align, then there's a problem.  I had this happen with a Smith lower that I bought.

This is wierd I bought 6 bcm midlength uppers and mated them to the spikes lowers just a few months ago . All of them fit and matched perfectly. I would say something is off with one of them. Would be hard to tell though without another to compare it 2. The good thing is both company's have stellar customer service. Good luck.

Process of elimination. Do you have a friend that owns ARs? If so, see if the upper will fit properly with his/her lower(s). Try multiple other lowers if you can. If you find that your upper fits well with another lower then the Spike's lower is likely out of spec. I had this happen with a Noveske lower & had to send it back for a replacement. It happens; no biggie.

Did you try it without the buffer and buffer spring. Once in awhile the rear lug has sharpe corners and hits the clearence in the lower.

Thanks Tom, the reason I went with Spikes was the reputation for customer service - I see I chose wisely.



But, being new to AR's, I'm not ready to point a finger at anything but me right now. I'll try the suggestions given in this thread - I promise I'll call Spikes somewhere between the "bloody fingers" and "kicking the dog" phases of the project.





 

All - thanks for the suggestions. I'll work through my evening trying the suggestions. Will post results good or bad.

There's your new slogan, Tom.

"Spike's Tactical: for every dog LE shoots, we save another."

Ok, I can confirm that the DD Omega X rail is what is preventing the upper from fully aligning with the lower's pivot pin hole. I removed the four screws that attach at the DD "proprietary" barrel nut - it allowed the rail to wiggle a bit, but not enough to let the upper and lower align.



The Omega X rail clamps on their barrel nut, right? Because of that, I don't think trying to reposition the rail will do me any good.  At this point, I guess my options are:



1) Remove a bit of the rail near the rear where it's interfering with the pivot lug

2) Remove a bit of the shoulders around the pivot pin hole on the lower

3) Have a standard DD Omega rail installed instead



THoughts anyone??

That is what I call customer service....

Glad my new rifle will be 100% Spike's. I was on the fence about the LPK, but I think I will be getting a Spike's LPK and maybe their 10'' rail also.