6.5 Grendel Upper Build

I do like to locktite the barrel extension into the upper receiver never trued one so can't speak to that. I do believe a heavy wall upper reciever makes a diffrence I have a Slick side DPMS that is very accurate and I just recieved a couple Mega SBU uppers I ordered for a couple more precision builds
 
Thanks for the response. One thing I was told by a builder is that while lower to upper fit generally does not make a difference, when we are talking sub .5 MOA, it matters.

I checked the Aero upper to the Aero lower I have. Unfortunately, it's a somewhat sloppy fit in the front, leaving a lot of lateral movement. My Anderson lower is actually about 4 or 5 thousandanths tigher. I checked an HK 416 lower for comparison, and it's probably 16 thousands tighter or so.

So now I am looking at lots of variables. Looks like the front lugs on all the upper receivers I have are about the same, it slop in the lower that is showing up.

Anyway, I am going to research options on how to fix it, looks like a shim can probably do the trick, but I did find a builder that is going to true the upper and be the whole thing for a decent price, so I'm going to do my best to cover all the possible variables.
 
For barrel bedding I have had good results with: Bedded with Loctite 234772 Green 620 High Temperature Retaining Compound. It is specifically for filling press fit cylindrical voids.
 
The builder is going to go ahead and true and bed the upper and barrel. But my lower was a little looser (laterally, in the front), than I was happy with. It was fine for a regular AR, I supposed, but I am trying to get max accuracy. Maybe it matters, maybe it does not. In the end, I looked at a few lowers and found one that was tighter, so I just bought it. Can't hurt to have a few extra lowers laying around, I suppose. I will use the first lower for a run and gun build, or maybe a dedicated 22lr upper.

Or maybe I will just sell it at some point.
 
I have a forged Noveske Lower and Biller Noveske upper and it's so tight I almost have to use a punch to get the rear take down pin out.
 
I am not so lucky as that, wish it were. I know I could get there, but I blew my cash on other stuff (lilja barrel, HS National Match DMR trigger). If I had known what I know now, however, I could have just bought a better lower in the first place....but what's done is done, so I'll have to make due with what I've got.

Next time, however....
 
Warning! This thread is more than 9 years ago old.
It's likely that no further discussion is required, in which case we recommend starting a new thread. If however you feel your response is required you can still do so.

Recent Posts

Top