I built one a few weeks ago for an AR using Aero XL upper and bolt from Brownells. I have a cheap barrel from GLFA, probably switching to a Faxon. I have not had the opportunity to test it. I bought some factory ammo for the brass, looked for Star Line with no luck.
The most common loads I have read about are made up of Lil Gun or WIN 296. I was going to start at 36 of Lil'Gun and work up. 450Bushmaster.net has load info.