AR-15: .223 Upper OK on an Olympic style 9mm Lower?

[marklbucla]

I understand that I can stick an Olympic Arms type upper on a lower set up for .223 without any modification. Does it go the other way? .223 Upper on an Olympic 9mm Lower without modification?

 

[Mute]

Assuming the 9mm mag block is removable than yes. As to the 9mm upper on a .223 lower, you will need to change the buffer and the hammer.

 

[marklbucla]

Are you referring to the "Colt" 9mm system or both "Olympic" and "Colt/RRA"? I read that the Olympic system should just be a straight swap.

 

[Zach S]

Oly conversions are drop-on, the ones that use the sten mags are anyway. If your lower is using the modified sten mags that Oly ships with the rifle, you should be fine. If it has a mag block to use un-modified sten mags, it will have to be removed.

If you have the Oly glock lower, I think you're out of luck. I dont think they have a removable mag block, but I havent handled one, or done much research on them either.