Sure. I bought a .375 AM built on the Gibbs .505/ Chetac case from Kirby Allen some 10 years ago and it's a great rifle and took mule deer out to 805 yards and elk to 636 yards. I asked him to build me a 3000 yard capable rifle and based on his experience with Blacksunshine, a .338 on the same case ( if I remember correctly he and his brother shot a prairie dog at some 2500 yds with it), he recommended a .338. That was also about the time the Berger .338 hybrid was becoming available. It took some time to get it together, partly because of parts and the first barrel was a dud so he changed to a Bartlein. Kirby is a true professional and delivered on his promise. He was not happy with .75 MOA at 1200 yds! The rifle has a BAT single round action. Stock is a simple McMillen. Big muzzle brake. For the .375 I have 10 round magazines and also 3 and 5 but I don't use them. Maybe single is stiffer and more accurate but I don't think much difference. My other .375, a single action Snipetac is about the same in accuracy - 2.5-4" at 1000 yds. I ve never gotten away from SMK .375 (always worked for me, blasted big holes, and no 'penciling') and GC rounds but the new .338 Berger seemed promising. I liked the carefully tested G1 and G7 numbers. I use a custom shooting rest prone.
What has been a pleasure is the Applied Ballistics and Shooter programs are spot on for vertical adjustment. Horizontal adjustment though is not as accurate, at least not for me but that maybe because of scope cant although I ve checked that. The round maybe drifts a little more with wind but to keep .25 MOA to .5 for long range is a pleasure for confidence. (I know the BC is better so should not matter) I use a 12-50 S&B scope. I have a 40MOA bridge so I have to zero it beyond 100 yd. I first made the mistake with my .375 AM of zeroing at 400 yd but from going from 1000' to 6500' causes problems with calculations etc. Unfortunately the scope is an earlier one with Mil reticle so I use the 2 Mil mark above center reticle and use this as my zero at 100 yd locally and at 6500 (you always check your zero don't you!? Learnt my lesson). Groups .25 at 100 yd or less but I only shoot 3 shots a never get it hot. 2 Mil, That's 7.2 MOA so for shots beyond about 600 yd I just subtract 7.2 from the calculated MOA and use the center of the reticule. Not ideal and I shot over an antelope at 1240 yd because of a miscalculation! Also for less than 600 yd you have do the calculation by subtracting the difference. Since the S&B has some 75 MOA range, I can get out to 2650 and more without using the reticle for hold over. I tried just over 3000 yd but could not see the strikes and I suspect that may be partly from dropping through the sound barrier. Not sure. Since I ll probably only get about 700-800 rounds through this barrel and it's my go to LR hunting rifle I m not going to burn up the barrel or bullets to figure it out.
Trust that is helpful. Cheers.
