AR Upper Interchangeability

Hello THR,
I have recently purchased an Armalite AR-15 A-4 and i have a question. I heard that I can buy an ar-10 upper and use my ar-15 lower and it will work fine. Is that true? Thanks for the help.

ar-15 is meant for .223 or alike cartrages and has a magwell to fit such. the AR-10 is meant for .308 or like sized cartriges and has a larger mag well that will not exept ar-15 mags meaning that .308 mags will not fit into a ar-15 magwell.

Nope will not work. You have to stay with cartridges in the 2.26 OAL range. The .308 round is too big for the mag well. There are a lot of calibers you can get for it like 6.5 Grendel, 6.8 spc, .50 beowulf to mention a few.

Nope.

You have to stay with ar15 uppers. You can swap uppers for different calibers, setups, etc. But they have to be ar15 uppers.


The AR10 is a whole different beast. It's upper and lower recievers are much larger and heavier for longer rounds like .308.