The .338 Lapua Magnum
By Chuck Hawks
The .338 Lapua Magnum dates back to 1983 when it originated as a U.S. military project. The design goal was a 250 grain bullet at 3000 fps. Early experiments conducted by Research Armament Company in the U.S. used a necked down .416 Rigby case, but the ultimate version of the 8.58x71mm (.338 Lapua) is based on a new and unique case.
In 1987 Lapua of Finland commercialized the cartridge that now bears its name and secured CIP approval. (CIP is the European equivalent of SAAMI in the U.S.) The cartridge caught the attention of Scandinavian moose hunters, and today Lapua and Norma of Sweden produce factory loaded ammunition in .338 Lapua. Commercial cases use Boxer primers and can be reloaded. Dakota and Sako offer rifles in .338 Lapua.
The .338 Lapua Magnum uses a large but conventional rimless bottleneck case. It has a rim diameter of .588", a base diameter of .587", and a shoulder diameter of .544". The shoulder angle is slightly more than 25 degrees. Maximum case length is 2.724" and the overall cartridge length is 3.681". Bullet size is .338". It is an impressive looking cartridge.
Lapua factory loads drive a 250 grain Lock Base soft point bullet at a MV of 2974 fps, or a 275 grain A-Frame bullet at a MV of 2581 fps. The 8.58x71mm military load uses a 250 grain spitzer-boat tail FMJ bullet at a MV of 2950 fps with muzzle energy (ME) of 4830 ft. lbs. This round is considered effective for sniping at 1500 meters.
I have seen reloading data that indicates that a 250 grain bullet can indeed be driven at a MV of 3000 fps with ME of 4995 ft. lbs. from the .338 Lapua. A quick look at the "Rifle Trajectory Table" shows that such a load using the Nosler 250 grain Partition bullet (BC .473) would have a maximum point blank range (+/- 3") of 298 yards, similar to the .300 Rem. Ultra Mag or .300 Weatherby Magnum shooting 200 grain bullets at similar velocity.
According to the fifth edition of the Hornady Handbook of Cartridge Reloading (which is more conservative than some) a 225 grain Hornady Spire Point hunting bullet can be driven at a MV of 2500 fps by 80.7 grains of Winchester WMR powder, or to a MV of 3000 fps by a maximum load of 95.4 grains of WMR. The ME of the latter load is 4496 ft. lbs. At 200 yards the energy is an impressive 3212 ft. lbs., and at 400 yards the retained energy amounts to 2236 ft. lbs. Zero that load at 300 yards and the trajectory looks like this: +3.5" at 100 yards, +4.6" at 200 yards, 0 at 300 yards, and -11.1" at 400 yards. (Hornady figures taken from the 24.5" barrel of a Sako 995 rifle.)
The recoil and muzzle blast of a .338 Lapua Magnum rifle shooting a 225 grain bullet at a MV of 3000 fps is fierce. According to the "Rifle Recoil Table" the shooter with a 9.5 pound rifle is looking at 37.2 ft. lbs. of recoil energy. Loads with heavier bullets will kick even more. It is strongly recommended that any .338 Lapua rifle be equipped with an efficient muzzle brake, and that the rifle be fired only when the shooter is wearing maximum hearing protection.
There is no doubt that the .338 Lapua Magnum delivers terrific energy at long ranges. The "Maximum Optimal Ranges for Big Game" table shows that the .338 Lapua can take 1000 pound animals at ranges in excess of 400 yards. (The actual range is 442 yards.) Whether anyone is ever justified in shooting at heavy game at such ranges is another question.
Copyright 2003, 2012 by Chuck Hawks. All rights reserved.