I promised a couple people I'd post up some results when I got my ARP barrel up and running. It's 20", 1-8 and threaded 5/8" muzzle. It takes a .136 Grendel bolt and that was the hang up. I ordered a bolt from Underground Tactical since ARP was out at the time and though it arrived the same day as the barrel, it was a dud. Sent it back, and received a second dud. That ordeal took nearly 2 weeks so was kind of bummed I couldn't play with the new toy. Actually I did manage to get a few shots off just messing with function, no real paper testing.
Finally ordered a bolt from Young, and what a beautiful piece of machining mastery. It's also heavier built with thicker walls around the case head. It's chrome, and engraved or printed with info, their logo, etc. So today was really the first chance I've had to get it on paper. The wind was howling from the east, but with a front moving in from the west I though I might get a few minutes of calm as it switched. I was right.
Working with 55 gr Varmageddon hp's, and 8208. I started with 31.5, moving up .3 gr. 31.8 gave quite a bit of vertical. 32.1 was better but moved to 32.3 and got pretty fair. Started seating deeper and testing and think I hit the sweet spot on the last group. Here are the last 2 groups, note the difference in depths. The left group is actually 2 groups, 7 shots total. The right group is 5 shots with a fairly warm barrel so hopefully it hangs in there cold. I ran out of daylight and prepped brass at the same time so called it good for now. Distance is 150 yds. The dots are 1".
Pretty impressed with it for a $200 barrel.