I did some load development for a friend of mine who had an AR 30. My first thought was "why N L would anyone want one????.....SUPRISE!!!! It was a real shooter. It never shot a group over 1 inch at 100 (3 shot groups) during breakin-load development, and I think the final load came in at around a half inch. It was a freakin chimney to clean during break in, but got much easier to clean at around 100 rounds. It ended up with moderate loads of H1000 behind a 250 SMK. I wish I had tried 300 gr MK. I was under the impression that it had a 1-12 twist....WRONG......1-10..... 300's would have worked very well is my guess!
The only problem I have found is that after the 2nd firing it is starting to split some necks. I don't have a clue why. The loads are mild and I am a ZIT when it comes to gunsmithing.
He has another lapua built on a weatherby action by Clay Spencer. No problems with that one!! My guess is there is a chamber issue with the AR.