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This makes me happy - thank you for the update. I mean that.

Get the Armalite AR-10 rifle gas tube (15.500") in that thing, as quick as you can. Please, for the children and the kittens. Retest it after that, and you'll see your ejection pattern change drastically.

8.2lbs, irons only, no mag. You start adding what you need, and 2lbs of loaded 20-rd mag, and it's a pig. That's the weight for the 20' barreled version, and NOT the heavy-barrel SSR. That fat girl comes in at 10.7lbs, irons only, no mag...

That's a pretty good score for a PA-10!!!

WOW!!! That is THE SHORTEST gas tube I've seen in one of these things!!! What gas system is it running? It's either midlength or rifle gas.

But - what gas system?...

Pistol-caliber ARs running on blow-back operation are REALLY HARD on hammer pins - just from the blowback operation. You run longer barrels than in a "real handgun," so you get a velocity boost out of them. Blow-back is hard on hammer pins. The KNS Prec non-rotating setup is tough, and will take the punishment. Those are the exact ones I use in mine.

That is a REALLY smart approach to take - that's awesome! Learn what you can ahead of time, then figure out what you want to do and which way to attack it - that's damn smart. Welcome aboard.

That's a pretty damn great idea, right there.

You can see the node coming in, towards the 23.6gr charge. Run that one,and run another test - higher by a 0.1gr or two. I've never seen anyone run ladders at 0.1gr spread - that has to suck. I run them at 0.3gr spreads, narrow in, then run than at 0.2gr spreads. I stick with the 0.2 that works the best. The only other time I've deviated from that is running my 5.56 75gr Hornady BPBT loads at 0.1gr, then finalizing. I will probably do that with my Win Mag, as well (0.1gr spread) as it's the only one I've got.

The B&T platform is amazing technology. Very solid. I only wish I could justify spending the $$$ for one. They're badass.

Any pistol caliber AR that you guys make, that's blow-back operation, better have some KNS anti-rotation pins in it, or you're breaking a hammer pin. Mark my words. I have a 9mm and a .45ACP.

Not yet. Armalite AR-10 Carbine gas(longer than AR15 midlength) on a 13.5", though.

Yeah, then those fuckers HACK the PSA website, find all orders for standard-capacity magazines destined for CA - and they have a "list." Not long after that, they start the no-knocks, and kick your door in to raid you...

There absolutely MUST BE a correlation to that slot in the mag body, and the centerline of the BCG. No other way around it. I have no idea what that measurement is, but you could find it from Armalite AR-10 prints - because it is the original, and it always works. The reason there MUST BE a correlation to that, is - the bottom of the bolt face has to strip the next round out of the magazine during the cycling process, when the magazine is seated and locked. The bolt face takes this force, because of the cam pin - the cam pin isn't allowed to rotate until it gets to the cam pin cutout in the upper - that bolt is locked in place in the BCG body, extended, while the cam pin is traveling down your charging handle groove, in the upper receiver - it's solid, not moving into the BCG body - and stripping the next round. Now, there will definitely be some variance, or tolerance, in what's too high and what's to low, in the relation of those two parts - but it can't be much. 20-thou? 30-thou? I don't know. Within limits, manufacturers can do whatever they want for mag catch placement in the lower - as long as they are within that range or tolerance in BCG centerline over the top of that mag catch. And it will work. They are working within the limits of their own upper AND lower receiver dimensions to achieve that distance between those two parts. If a manufacturer fuks that up - your gun doesn't feed/strip the next round, OR the BCG slams into the back of your mag body. It can only be those two things. This is the beauty of "not having a standard or pattern to follow..." I will measure the 4 previous rifles I listed - Top of mag catch to BCG centerline. I'll bet it's pretty close on all of them, despite having a difference of 30-thou in mag catch placement over the 4 guns.

The top of the mag catch is what holds the mag in place. Now, a slot that's way too wide (over 0.250") would allow the mag catch to "rotate" down in the too-wide slot, which would effectively lower the seated height of the mag. But the top of the catch is what determines mag height - and retention. A fully loaded 20-rd LR/SR-20 PMag weighs 2 lbs. The top portion of the mag catch itself, and the top of the indentation in the mag body, is what determines the height of the mag when it's seated. That business is all determined by the top of the mag catch, and this - this is what the 2lbs hangs in the gun from:

This looks like is might be pretty good...

There are still some great companies out there. I'll pick up a few Hex Mags just because of this.

I've got a couple of the extended scope mounts, and one extended 30mm red dot mount - they're great.

This is directly for @jtallen83 I saw this guy on the way in to work this morning, and I immediately cracked up, thinking about you, brother... Custom flatbed Dodge diesel, built by the sound of it, and some giant welder permanently mounted to the flatbed... Obviously, he's making good money... Check out the bottom of his mudflaps...

So, is this thing solved, man?... It functions now?...

Go hit my past posts here, man, and fire up some answers - what uppers and lowers are you working with here? This is the ground-truth, right here, in mis-matching manufacturers. I stand strong on this one - THAT is the major problem here...

I was only stating the measurements of the guns I could easily get to, and reported exactly what I saw on the guns I have. They all run, or I'd chop them up and sell the scrap, man. Personally, I was shocked at the differences I saw, because they all run like mad. The numbers I got were way off that first print number or 0.687", too. But they run... I don't have a single one that has a different upper than the lower, though. Same manufacturers, but way different numbers in mag catch placement. Of note, on measuring AP lowers - you can't accurately measure that lower if you don't disengage the mag catch, and rotate it out of the way. The AP lowers have a taper/chamfer on the top side of the lower shelf, that you can't accurately measure, if that mag catch is seated...

A manufacturer can put that mag catch placement anywhere they want, within obvious limits of the platform, brother. As long as they account for that "higher or lower" placement in their exact placement of that BCG channel that they bore in the upper - on their own upper that mates to that lower. They can literally do what they want, within functional limits. When people try to match different uppers and lower from different manufacturers - is when we see these issues. Or, you try to by an IRA billet machined matched set that never worked from the get go, because the dimensions were off, fundamentally...

From @panel77s history, he started with a PSA upper, and machined his own lower from Blitzkrieg or AMT, if I'm not mistaken. So, right off the bat, you've attempted to adapt a self-proclaimed proprietary upper onto an 80% lower, that you machined (or someone machined). And, there's a question as to why there are issues now.