WestKentucky
Member
I traded into a slightly used UTAS XTR12, and have not found any really solid answers to a couple questions I had. First and foremost, is the LOWER actually as described... an AR10 DPMS pattern lower. I don’t have an AR10 to compare it to so I found a spec sheet that looked complete at the time (good but not complete prints) and today I got around to measuring and comparing.
Let’s get the nit picky points out of the way first. There are 3 patterns that people call AR10 patterns. The DPMS is technically NOT an AR10 but it’s what most people are referring to as when they say it. The prints I have specifically say they are for DPMS pattern lowers. No I’m not sharing prints because what I found appears to be proprietary drawings that slipped out of the manufacturers files. Drawings are available with a quick search, but typically don’t have as many numbers called or references as nicely displayed.
On to the UTAS.
There are very few slight differences that are notable.
Difference 1
The width of the lower is notably oversized. This seems sensible since the upper also is slightly oversized to accommodate a shell much larger than the original design allowed for.
Difference 2
The depth of the pocket at the rear takedown pin is about 12 thousandths deeper than called for. Takedown pin location is correct, pocket depth is deep. This should not cause issue at all.
Difference 3
Exterior shape is always unique to the manufacturer as everybody puts slightly different lines on the forging. This one would have a notably different shape along the top of the reciever. The wide/thick rails along the top of the reciever make the whole exterior across the top a bit fat. Should be purely aesthetic but could potentially cause it to feel weird if you gripped that area while carrying it configured as a rifle.
All other measurements seemed to check out. Trigger group pins, trigger pocket, center to center points on takedown pins is a calculated number that was within 7 thousandths but my calipers aren’t long enough to measure 7 inches so I had to combine measurements and try to work it out from other reference points. Being that close I’m calling it good because there was definitely some operator error in trying to get those measurements. .275 takedown pins, and my rear pin is super tight (tap in with delrin faced hammer tight).
So is it an AR10 pattern lower.... I’m going to say.... basically. I think an AR10 upper will fit and work, but I don’t have one to try. The differences are slight and would not interfere.
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