I knew I should’ve started this build in early July back when these uppers were in stock:( and were even on special, I’d have something shootable by now.
If anyone knows of a BCM 20" barrel or upper, please let me know.
What do you guys think of my build plan?
Only thing that seems “iffy” is the drop in rail but I have free floats on the rest of my AR’s so I’ll stay with the MI rail til I can get a FF.
The same thing happens to me. So today I was cruising BCMs site and saw that they had everything in stock for a complete upper I’ve been wanting, but not necessarily needing… So I ordered it.
I’m still waiting for those goddam Magpul XTM ENHANCED rail panels, they keep moving the date
In the end I decided not to screw the thing and left the VLTOR MUR out of the build. If I were going with a FF rail from the begging with a proprietary castlenut I would of gone with the MUR but I’ve had a very hard time with standard castlenuts and MUR uppers. In my last build I had to grind down a notch in order to Torque to spec, otherwise I just couldn’t align it properly until 80+ toque and I really wasn’t comfortable with that.
I got lucky, came across a guy that had a brand new one unfire, BCM still has yet to get these uppers back in stock.
Nice setup you got there. However why are you holding out for the enhanced XTMs versus the standard ones? Is it because you’re planning on getting rid of the AFG and replacing it with the integrated handstops on the new XTMs?
The problem isn’t the parts. It’s your understanding of how the nut is to be torqued. The minimum torque value is 30 ft./lbs. That means if you hit 30 and you are lined up, then you are good. 80 ft./lbs is the absolute maximum.
Generally the problem arises from people not understanding how to do the install properly. I don’t use a torque wrench and I have never had a nut come loose, nor have I never been able to get a nut set right.
The problem was the teeth on the barrel nut. If I were using a barrel nut that didn’t have teeth that stick up such as the SWS nut or the VLTOR VIS nut I would not have this problem and we wouldn’t even be having this conversation. If I were to just adjust until the next notch, it would be WAY to tight. If people feel comfortable tightening that hard that’s up to them. I would have to physically show you what I am talking about in order to have a better understanding.
I don’t see how grinding down 1 tooth of the standard barrel nut could be bad for the barrel nut. Plenty of proprietary barrel nuts don’t have teeth that stick up.
Well, I got mine on without issue. Cleaned the threads on both the MI Barrel Nut, and the upper, lubed them, torqued to 30#, backed it off, torqued again, still needed another 1/4" turn and kept increasing the torque until the teeth lined up. 50#. Backed it off, and repeat, same torque to get the teeth on the barrel nut lined up.
