First Pistol Build

Like it says, this is not only my first pistol build, but my first experience period with an AR pistol.
I have to say, I was expecting WAY more of a violent recoil impulse than what I felt and I was pleasantly surprised and duly impressed. The damn thing is extremely smooth and flat shooting. I just don't get it.
I took it out today, in the rain, with the intention of just firing it to check function, just make sure it fired and didn't blow up. Intending to fire 10 rounds or so and use the rest of my 90 rounds to do a barrel break-in on my 16" RECCE (which I've yet to fire) but it came such a rain I just put all 90 through my pistol.
I'm happy to report that it functioned perfectly. No malfunctions of any variety to report, ejection pattern was at my 4 O'clock and about 7 or 8 feet away, all in a nice little group, very pleased to see that.
Muzzle flash was absolutely horrendous though, there is a huge bright flash with every shot. Hell, I thought it was lightning at first because I was standing in the middle of a storm. Wow, that's one hell of a flash. But then I noticed how controlled it was though, definitely not what I was expecting. It is really easy to shoot quickly, so, I did just that letting about 5 go, doubles, triples, doubles and so on till the bolt locked open. OK, that works.
I was shooting at 4 8" steel plates about 40 yards downrange and the melody was quite nice. I had taken off a Burris ff3 from another rifle and mounted it on the pistol with no adjustment and was banging gongs with ease. I know, 40 yds, whoopty doo but I was hitting them, AND it was pouring rain. ;-)
I started with a billet upper and lower from Next Generation Arms from back in about 2012, really nice billet receiver set that are very well fitting to each other and the lower also has a tensioning screw be hung the grip to take out any play from wear, there is no play now, they're nice and tight. I fitted it out with a LPK from CMMG that has an ambi safety. I did buy a set of BAD Titanium pins (pretty nice), a Magpul MOE K2+ grip that I love, I think it's my new favorite grip, if it was just a tad bit thicker it would be perfect. I also used a receiver extension and qd endplates from NGA, both billet 7075 just like the receiver set. The tube is an 11 position tube, yes, 11 position, and it's really, really nice. I'm using a stock carbine spring and an H1 buffer. I finally got to use my SBA3 brace too. Also my first experience using a brace and this thing is fantastic, it's comfortable and rock solid. I was worried about using a brace, that they would not be as stable as a normal rifle stock, man, was I wrong. No worries with this thing folks, it's solid and steady, again, impressed.
I almost exclusively use BCM Bcg's and charging handles and remained true to form here. CH is the mod4, medium latch.
I had initially intended to use this lower for another rifle and so had installed my Geissele SSP in it and didn't change it out after changing direction. What can I say, it's a Geissele, it's they're only SS trigger, and it's sweet as hell.
I bought a Daniel Defense Mk18 barrel, gas block and tube from a forum member and I couldn't be happier with it. I don't know what level of accuracy one is supposed to expect from a 10.3" barrel and I didn't try to find out on this trip, remember, it was pouring rain, but I'll find out next time. The barrel is really nice though and I'm happy I found it here. I put a BCM Mod0 comp on it and I'm wondering if that's why I was shooting lightning out of that little barrel. I'm also wondering if that's why it was so controllable. Either way, that flash has to go, at least as much as I can make it go. Any suggestions??
I cheaped out on the rail and bought a Guntec m-lok 10" rail. It's actually alright. It's light as all get out. It's very slim and easy on the wallet. I don't like that it has an aluminum barrel nut but maybe it will be ok. It didn't move at all during fire, it never got hot either. There is almost nothing to the damn thing, it's very open so I guess it should stay cool.
So, there is my newest build and my first pistol.Attachment 52412
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I just wanted to show a little bit more of the machining details of the receivers. The mag well is cavernous but internally it holds the magazine solidly. The integral trigger guard is machined in such a way that it forms a great finger rest, a comfortable place for the pad of the finger, not inside but right there where it flares into the rear of the mag well. I like that. And of course the forward assist-less upper. It's nice and trim, and sleek looking. I think it looks pretty nice.
I actually bought 2 of these uppers, 2 with the FA, and another that is a forged upper. The forging is from Brass Aluminum Forging having the offset square. All of the uppers have M-4 cuts.