View Full Version : AR-15 Lower. What Upper Calibers Fits.

02-15-2012, 5:11 AM
I like the looks and prices of these CA compliant New Fronteir polymer lowers but I was wondering what type caliber upper will work with these. I "assume" that I can get uppers in .22, 9mm, and .223 but will these lowers work with anything else (7.62x39, 6.8, etc). Maybe with a beefier buffer assy?

02-15-2012, 10:03 AM
Dont know what kinda buffer you would use (I bet there are specific ones for some of the different calibers) however check these links i found doing a quick google/calguns search. I think they hold the info you seek. With that said, it may not be the smartest thing to put a 50beowulf on a POLYMER lower...



02-15-2012, 10:06 AM
They should be compatible with any caliber that fits the Ar15 platform. The lower is just a place holder. It does not take much stress during firing.

02-15-2012, 10:09 AM
.22lr 9mm .40 .45 7.62x39 5.56 .223 i even think .50 beowolf will work

02-15-2012, 10:42 AM
I posted a thread on the New Frontier lowers about a week ago. Many dozens of responses (look back to last week). Anyway, a number of folks commented that the hammer may be too wide to work on a .22lr or 9mm conversion.

So - if you do decide to pin one of those uppers to this lower you might have to make some changes in the FCG.

02-15-2012, 5:22 PM
Thanks folks, I thought the answer was all of them. I did think that maybe some rounds may not be able to fit in the mag well like .308 or .410 shotgun. Good info. I think I will pick up one of these before heading to CA for an extended visit.

02-15-2012, 5:30 PM
I did a google search and quit counting at 40 different uppers. From .22 to .50 BMG (single shot) and also .50 Beowulf. I also found a crossbow upper for it if you want to drop $1K. The bb gun upper is insanely expensive for the POS I found.