I recently purchased the Professional in 300 win mag. I topped it with Warne rings and a Leupold VX3: 4.5-14x40 (Parallax is an issue - big mistake on my part). I've got 37 rounds down the tube so far. The first 10 rounds were break in rounds (shoot-clean-shoot), followed by standard load development with 3-shot strings and random cleanings.

Honestly, the first few shots were exactly what I was looking for, right around 1-inch. Those first 10 shots were break in shots consisting of a fairly decent load of H4831SC and 180 grain Hornady BTSP Interlocks (only had 10 at the time). That being said, it's really hard to definitely say what it was doing between cleanings and a cool barrel - not a 4 shot group.

My goal has been to shoot Nosler A.B's and/or Nosler Partitions. So far, it's pretty obvious the rifle doesn't like either of them. But like any other narrow minded rifle looney, I'm going to keep trying because I just bought a box of 200 grain A.B's.

I found another box of Hornady 180 gr BTSP's that I'm going to start over with. Maybe I got lucky and found a node and a bullet the rifle likes...

I'm just sharing my experience so far and will update the group as I continue load development. This rifle reminds me a lot of my "former" Kimber Montana 300 WSM. The Professional is a dream to handle, but its pretty hard to shoot accurately. The muzzle break does help. But.. It's still a relatively light weight rifle. I purchased some snap-caps to work on my technique and trigger pull. Maybe that's part of the problem folks are having.

I know that Petzal's review of the rifle clearly discussed his challenge and frustration with finding a load the rifle liked - And I think he was using factory ammo.

Bottom line is that experience is telling me this rifle is going to take some effort to figure out. I was hoping for out of the box idiot proof, but it's obviously going to take some finesse. I'm trying to not get discouraged by reading some of the comments on this thread as well. Sure there's a lot of rifles on the market far cheaper than the L.A.W. The L.A.W has some bad-ass components, far exceeding all of the similar priced competition! I love shooting paper targets, but I also love a rifle that looks and feels as indestructible as the Professional! And, when my brother accidently throws a bone saw at the stock when we are gutting my elk (like he did last year to my 300 H&H Ruger No. 1), I won't lose as much sleep!