I am looking to do a build for an AR 15 5.56 around the Rarebreed FRT 15 trigger.

Not completely unfamilar to guns. But builds I have never went after.

I've talked to a couple of people on lowers and I am getting mixed answers.

Ultimately looking for input on which lower would be ideal to start on?

For those that are not familar on these triggers. The gun will run hot, fire rate will be much like a binary trigger.

I know most of my specs i am looking for on the rest of the gun but lowers I am not seeing much on that makes a difference. But i know your starting point if not thought out properly is going to dictate this build and longevity down the road.

Thanks for any and all help.

Lower is not really the issue.. just get any decent low shelf lower.  

You'll need to make sure you have a full auto bolt, and a barrel that can withstand full auto fire.

You're going to need an H2 buffer... and I wouldn't skimp out on the BCG.. get something nice.

The BCG is the key, get a good Toolcraft and enjoy.

Chrome lined barrel not super common any more since most due QPQ for accuracy,  but Chrome lined will hold up to full auto fire along with a heavier barrel profile.

Lower won't matter might think about anti walk pins.