338Remington Ultra Magnum
When unpublished word was getting around in some circles that the 338 Lapua wasn't inherently particularly accurate, I wasn't interested. I already had a couple of rifles chambered in 340 Weatherby Magnum at the time, and they both shot in 5/8th-inch territory. Now keep in mind, that was before I got the Ed Brown Marine Sniper, which shoots sub-half-inch clusters, and consistently under an inch at 200 yards. So, no need for a 338 Lapua; a cartridge that had been receiving grumbles from knowledgeable shooters whom I trust.
But what about the 338 Remington Ultra Magnum (338 RUM)? The 300 Ultra Mag was certainly capable of match accuracy, so the 338 RUM at least seemed promising. Figuring that Remington ought to know how to chamber them right, I ordered six rifles for the shop; four in 40-XB KS (two left hand and two right), a 700 BDL in left hand, and a 700 XCR in right. The 40-Xs, of course, were single shot. The 40-XB left-hand rifles went to men capable of shooting heavy recoiling rifles off the bench, the BDL went to one of them for off-hand testing in the field, one of the right-hand 40-Xs went to a fellow who has yet to wring it out, while the other 40-X and the XCR stayed with me. That last 40-X mentioned was also special ordered with a 9-inch twist instead of the usual 10.
The rifles, all of them within their respective class (target or hunting), are superbly accurate. Factory test groups for the 40-Xs were all in the .60- to .70-inch range. They never shot that large a group for us. Actually, those measurements reflect what we were able to get at 200 yards, with some groups going under an inch at 300. The best bullet for accuracy so far has been the 250-grain Sierra MatchKing. The best powder has been either Re 22 or Re 25; it's hard to determine a difference out of these 27.25-inch barrels. The 300-grain MatchKing and other heavy match bullets shoot as well as the 250s out of the 9-twist rifle, which is not the case with those of 10-inch twist. However, the 9-twist rifle does not shoot the 250s as well as those with the 10-inch twist. There may still be a combination discovered that makes the 9-twist rifle worthwhile, but at this point I'd recommend the standard 10.
In our opinions, based on firing plenty of rounds in favorable conditions from several rifles in both chamberings, we believe that the 338 Remington Ultra Magnum is considerably more accurate and more consistent than the 338 Lapua. Further, we believe that the military chose the wrong cartridge for its long-range work. One of our mentors truly believes that part of it is the designation; "Lapua" sounds cooler and is easier to say than "Remington Ultra Magnum."
Those familiar with the 300 RUM are surprised when they see a 338 RUM cartridge. Both the body and overall length of the 338 RUM case is shorter; the neck a little longer. It would have been easy for Remington to simply neck up the 300 RUM to accept 0.338-inch bullets, but we understand that the development work also included exhaustive accuracy testing. Further, the 338 RUM is right at full capacity with a number of suitable powders, while the 338 Lapua tends to run at about 90 percent full.
In the light 700 XCR, and the almost-as-light BDL, recoil is swift and solid. We've taken these rifles out with friends to shoot and, even offhand, many of them are reluctant to try more than a few rounds. For the XCR, a load was worked up using the 275-grain Swift A-Frame. At 2750 fps, this rifle is as powerful and flatter shooting than the 375 H&H. But is it a good choice for Africa? Probably not the best, because it has never become very popular and replacement ammunition will not be available in many areas.
At least one bullet manufacturer has stated that the 338 RUM is so accurate, they are now using it to test the quality of their own 338 bullets. Now that's something.