Dumb AR question

[5thstreet@sbcglobal.net]

I did a search but couldn't find anything useful so sorry if this has been asked before. I know you can put a .223 upper on a 6.8 spc lower but can you put a 6.8 spc upper on a .223 lower?

[69Mach1]

Yes. Although they can be marked with different calibers or not at all, the AR15 type receivers are all milspec and compatible.

[Saigon1965]

Slap her on and your good to go - Just make sure your not mixing cartridges