I was gifted an AR10 upper and had no plans to build one, but now with a free upper, I feel like I at least need to complete it. So, I need a complete lower.
I do not know what brand upper it is as it has no markings. The fit/finish is nice, and it seems to be well put together. I have looked online (PSA) and found a lower I like but, I want to ensure it will fit as I don’t want to get stuck with a lower that isn’t compatible.
I have found one I like (see below) and am hoping that it being a Gen 3, will work with my upper. How can I know whether or not this lower will work with my upper or can I without trying it first?
Most people will tell you that there is no ‘standard’ for AR10s. However, there are a few ‘patterns’ that most use. DPMS is a popular one and I think that is what PSA lowers/uppers are modeled after. Again, I think it is. Any markings on the upper that you could research to see who made it?
I believe you are correct Sir (the-mechanic). It does appear to be an LR308.
As for asking the person that bought it, he is no longer with us. He passed a while back and the daughter gave me this upper and a bunch of other miscellaneous firearms related items.
So, now that I at least know that it is an LR308 and not an AR10, does that help with a lower selection?
FWIW… the PSA lowers and IMHO, while very close to a DPMS pattern, there are subtle differences. ( Remember, No Mil-Spec guidelines for Large Frame AR’s )
The PSA uppers BCG rides slightly higher than a “true” DPMS upper BCG.
And that means the positioning of the mag catch with a PA10 lower is in a slightly different position then a DPMS lower.
Why does this matter ? Ammo feeding . And bolt catch function.
Next the upper to lower assm. lugs / pin holes might not line up properly… and it “might” fit together… but the items I have listed will not be “quite” right.
I tried a Aero upper and a LR308 ( DPMS ) upper on my PA10 gen 2’s… the differences in fit were enough for me to stop trying to get other brand uppers to work with the PA10 Lower.
That does look like the handguard on my upper, even down to the “USA” on it near where it attaches to the upper.
I went by PSA the other day with my upper to see if they had one that fit. They were pretty busy and the nice young man that waited on me was not very knowledgeable about this platform. I tried one lower and while it fit, it was tight. I got the front pin in, but the back needed a tap, and I didn’t want to that in the store. Perhaps I’ll go back and look again and see if I can find an associate that is a bit more well versed in this platform.
i think you’d probably be ok with a psa AR10 lower receiver. there are manufacturing tolerences that may make its fit and finish from upper to lower a bit tight, or a bit loose. the big thing i would / was worried about until i saw your photos was the differences in between the DPMS style and the Armalite style AR10s. where the back of the upper meets on the armalite is much more angular than the DPMS style, which is much more l ike the standared AR15 being more of a rounded edge to the top of the upper. as you see in this photo:
Like i said, i think youre fine with a psa ar10 lower. especially if you can take your upper in to a store and try it on a lower first like you’ve obviously done. I would buy a lower from PSA with confidence pretty much.
Went by a couple of days ago and test fitted my upper to the lower I wanted. Couldn’t put the pins in as I was told they were not allowed to “assemble” a firearm in the store. Probably another silly ATF rule. Anyway, the pins lined up, so I took a shot and ordered one. Fingers crossed.
its the most rediculous rule if you ask me… but whatever… what if i broke down one of their ar’s on the shelf, does that mean they couldnt put it back together? what a conundrum!!!
Well, I bought a lower from PSA and while it was a tad tight, it fits just fine with no rattles. All I need now is a charging handle to make it go BOOM.
