Well I've stripped 'em and fixed 'em and modded 'em and maintainted 'em for years, but I'd never BUILT one from a bare virgin frame until today. Cherry EA preban lower and J&T parts kit. My question is, is it common to have to fit and tweak things on AR builds? Seems I had to do a little tweaking on almost everything as I went.

The dreaded pivot pin detent went pretty smoothly, using tips I picked up right here. Only lauched it across the room once before I got it in. That part actually went smoother than the trigger guard!

My biggest problem was that it wouldn't pass function check when I finished. The disconnector wouldn't disengage unless I prompted it with a punch or screwdriver. I don't know if the disconnector hook was too long, or the hammer hook was, or if the hammer or trigger holes in the receiver were off by just "that much," but I ended up solving the problem by Dremeling about .010" off the disconnector hook of the hammer. It clears fine now and still seems to have plenty of solid engagement when disconnected. Might find out if it really works tomorrow. I'll probably be using this lower for an M261 .22 conversion, at least for the foreseeable future.

The build took me the better part of the afternoon, and I worked on it an hour or so last evening, too. But as others have said, I think my next one will take half the time. Lot of the time was spent just picking out and making sure I had the right part. Next time I'll know going in what's what.

I put together my first one sitting on the couch watching TV. My tools of choice were a toothbrush, my Leatherman and a tap hammer. Pretty darn simple.

Congrats on the first build.  

Quoted: My question is, is it common to have to fit and tweak things on AR builds? Seems I had to do a little tweaking on almost everything as I went.

It sounds like something's out of spec on the receiver and/or the parts set.

I've assembled a few lowers and have never had to do any parts modifications.  I have had to overhaul a few rifles that were assembled with the cheapest parts sets possible, and fire control group problems were common with those.  Cheap cast parts from some company in Illinois...  Nesard, I think?  I make a point of sticking with FCG parts from a known source, both for safety (unintentional firing and doubling is a real danger with no-name parts) and so I don't have to deal with the expense and aggravation of identifying and replacing bad parts.

I haven't used parts from J&T yet, but they seem to have a good reputation here.  Keep an eye on the FCG and see if any wear starts appearing on the hammer/trigger sear surfaces.

I've assembled a ton.... never had to dremel anything.  Something is out of spec.  That aint right.  Hardly any tweaking on an AR for correct function.

In all my builds I have never had to tweak anything.  Sounds like something is/was out of spec.

Congrats on the new build though!!

Thanks for the feedback, fellas. I too suspect something is out of spec somewhere but don't know what. I suppose I could start swapping parts with known good guns and figger it out, but if it works as it is now, no big deal, I guess.

I think most of my problems were caused by the finish on the EA lower. It appears to be some kind of flat gray paint (pretty durable, though), not anodizing. For example, I had to clean up the selector hole on the right side and remove most of the finish in there because the selector wouldn't move freely. I put it in the hole and cowboyed it around until the wear marks showed me where the interference was. A few minutes with a rattail file and it was moving freely.

The bolt catch is also not moving freely, I suspect for the same reason. No big deal if I'm running it with a .22 conversion because those don't activate it anyway, but if I ever decide to shoot much centerfire out of this lower, I'll have to take that back out and polish out the interference.

I hate roll pins.

The trigger guard gave me a bit of trouble, too. The pins definitely didn't line up on that. Had to do a bit of filing to get it in. When the rear pin was installed, the guard was notably offset to the right by several degrees--enough to keep the guard from locking properly. I don't know if the holes in the receiver or in the guard itself were out of square. Again, not a huge deal. I made it work.

I've built a number of 1911s on aftermarket frames and there is ALWAYS tweaking of one sort or another to be done on those. Just wondered if it was supposed to be the same on ARs. BTW, I built four or five guns on Essex frames and never had any problems with the hammer or sear holes that so many have complained about, so maybe with this AR I was "due." But if it works, I'm happy.

When you say EA and gray finish, I assume you meant Essential Arms?  It is not a paint, it is anodized, just not black.  Anodizing is a process that chemically alters the surface of the aluminum, making it more corrosion resistant, and at the same time, porous enough to absorb dyes.  Essential used the original gray like on the early Colt M16's and AR15's.

Please resist the temptation to spray black Krylon on the lower.  Hah!  I have seen more ugly peeling Essential lowers than I ever wanted to.  I would rather see mismatched colors than peeling paint.  If you must, strip the lower and coat it with Duracoat or Norrell's or one of the other high quality baked on epoxy based finishes.

From the problem you describe with the FCG, I will say from experience, buying two rifle kits and also other parts from J&T, their lower parts are high quality.  But still, you occasionally run into problems with timing of the disconnector with any AR-15.

But sounds like you solved the problem.

Only 3 builds, and luckily no mods needed yet

Well, it appears to WORK okay, at any rate!

Just got back from the range, where I fired 8 groups with each of two kinds of .22 ammo. There were NO malfunctions of any kind other than a couple of misfires, which is pretty normal with the cheap .22 ammo I like. If anything, the old 1:12 upper/M261 combo seems to like this receiver better than its old one. Groups ran like this (5 shot groups @ 25 yards):

Federal Walmart Bulk:
1.080
.604
.645
.594
.324
.726
.332
.510
Average of the six best groups: .394"

Winchester Dynapoints:
.371
.748
.797
.382
.616
.262
.283
.198!!!!
Average of the six best groups: .352"

I'm VERY pleased--neither of my 10/22s and at least one of my bolt actions don't shoot this well! It shoots ALMOST as well as the DPMS .22 M4--but in honesty I should note that the DPMS shoots a 3/8" average much more consistently. Look at the numbers above and you'll notice there's a fairly large spread.

Still, I'm very happy with how this project came out, especially since my kid has pretty much hijacked the DPMS .22 gun. Now I have one to shoot too!