I'm currently having very solid results from the 338L improved to minimum body taper and 35degree shoulder. It does 2900 with the 300's with a 28" barrel and so far two barrels meet my 1/4 moa AGG requirement. It'll take 30-31" to make 3000 safely IMO. I don't like the standard 338 rd.
This is a really fine cartridge to base a 338 on, but IMO You need to spend some real time/money/resourcefulness on the stock/bedding/support. These things KICK, they hump up an ordinary setup like hitting a balloon wit' a baseball bat. This round, hopped up, makes normal stuff feel like you're shooting a flyrod.
I'm mod'ing an A5 McMillan as we speak, adding a top strap like a thumbhole because I think the stock is Tiggering on me, bad. (I know, the stocks suck for accuracy anyway, but I've got three of them setting here and have learned how to bed them...)
But, given a true BR treatment (scaled up!)
the case is capable of wonderful accuracy and good velocity. I've bedded a couple into my old red mule, original McMillan BR with the long flutes that's been chopped and filled and abused beyond recognition, it'll handle the recoil (now) and it turns in solid groups. I'm building an adjustment for the buttstock rail because I'm kinda' half convinced the cartridge needs to be pre-biased like a race car. It is my opinion that these setups MUST be indexed, possibly bedding biased for torque and preferably braked. But it must be noted that the brake does absolutely NOTHING during the humping up cycle....... the bullet's gone before the brake catches the rifle. If the rifle goes sidewise you may not feel pummeled but groups will suffer.
Gonna' fit a couple more this week...... I was scared the first time I wrapped my finders on the hannle of my reamer but with preboring it hasn't been a problem.
I don't know what it would take to make a Chey-Tac or BMG based 1/4moa rifle but I'd want to start the process with ten grand in my pocket. And I don't know that I could spec it..... would certainly bend
my peabrain
al