This is my airsoft p90 loadout, but the gear is all real steel. So it should work just fine with an AR five seven upper on your AR-15. No, that's NOT me in the picture.... My GF was trying on the gear as she wants to come out and play at some point.
On the left leg it's a 3-mag drop leg from (all gear in the picture came from there)
Right leg is a p90 dump pouch that I can use for the P90 and my small AK.
Then the duty belt and of course my Echo 1 p90.