LTLR,
I'm not the one who did the workups in the reloading data, for either the Sierra or Lapua manuals. I mention this simply because there is a tremendous amount to variation in the barrel lengths we're seeing in rifles chambered for the 338LM these days, particularly for those under consideration for the Precision Sniper Rifle contract fro SOCCOM. Seems to be a strong preference among some for very short barrels, which can make the 1,500m accuracy/energy requirements a bit tough. Hey, I can certainly apprecaite a lighter and handier rifle, but it's still gotta do the job once you get where you're going.
I used this cartridge as a standard accuracy round for my QC testing in the tunnel, and was always very impressed by it. There, I had the option of barrel length left to me, and generally ran 28-30" tubes on the various test rifles. Never had any reason to mess with anything shorter than that since (obviously) portability isn't an issue when dealing with a machine rest and barreled action. My concenr hre related more to those that have gotten ridiculously short, like some I've heard being pushed for the PSR competition. Once you start getting close to carbine lengths, you're giving up significant performance. That, and I sure don't wanna shoot it without double muffs and plugs, and someone else's shoulder against the butt!
Your velocities sound a bit high, maybe 100 fps or so compared to what we've seen in the manuals. However, as you've said, as long as it's not giving you any pressure signs and everything's functioning properly, you're probably fine.
Kevin Thomas
Lapua USA