I bought it off a friend real cheap (75 bucks)  he said he had a stripped lower so I drove out their and I figured even though it was marked 9mm i would buy it (the price!)

Should I build a 9mm carbine? I really see no advantage except cheap ammo but aren't 9mm's expensive to build?

Should I just build it 556mm, I dont think i would have to change anything but people would probably ask WTF???

Should I sell it and just buy a 556?

ttt

My advice -

1. Remove price from above post
2. Post item on EE for more than you paid for it
3. Build/buy gun of your choice with proceeds from above sale

Is there anything special about the lower that makes it '9mm' other than having that printed on the side?

Quoted: Is there anything special about the lower that makes it '9mm' other than having that printed on the side?

I dont think so, if its exactly the same I will build...

I'll buy it from you.2