Left eye dominant here. Shoot long guns lefty. No problems operating AR's. Like others have said, make sure the upper has a deflector and you're good to go. Last time Obama was elected, I had just bought a Bushmaster, but I ordered a Stag model 6, took 13 months to receive it.
Honestly, I've never even fired the Stag. Absolutely no issues shooting the right hander, lefty.