Question about uppers and lowers

[John A.]

Originally Posted by KEVWYO

OK then ... will the 6.5 Grendel upper fit a 5.56 lower?

Absolutely.

The only differences in them are the bolt, barrel chambering (obviously) and they use a dedicated magazine as the feed lips and followers are different than 5.56, but they will fit any spec AR lower with no modifications whatsoever.

Alexander Arms holds the copyright to them, but there are several other places making them.

At midwayusa, you can even buy the kit that includes all the necessary parts (bolt/barrel/mag) to change an existing upper for 6.5 grendel. And much less expensive to boot.

[fal guy]

even though you think I'm a sexist..

ar15 lowers won't work with a 308. however fulton armory(aka dpms) and
PoF make ar10 lowers. that will suit your 308 needs. fulton armory ones are less expensive, but you won't be able to fit chip mcormick or timney triggers in them. PoF is way expensive and I've had trouble using lower parts kits in them. they will use the same buffer tube's and lpk's with the exception of bolt catch , mag release and buffer spring. so good luck. uppers from dpms are made to fit the
platform, and are availible in 16" med con w fh's to 24" fluted bull's.

you can get a veriety of calibers to mount on the ar15 lower. 50 beowulf
7.62x39 22lr 6.8spc 6.5grendal and many others even 9mm and 40
check ar15.com those PEOPLE will be able to help you out.