Yearning For A .358 Norma Magnum
Q: I have a Schultz & Larsen rifle in .308 Norma Magnum with a badly eroded throat that needs a new barrel. I am interested in having it rebarreled to .358 Norma Magnum. A gunsmith has advised me that a .358” groove barrel with one calibre of free-boring is the way to go since it would be superior to a standard chamber. What is your opinion of the .358 Norma Magnum and this procedure? My other questions are: What would be the maximum velocities with Woodleigh’s 250gn, 275 and 310gn bullets. What effect would free boring have on these velocities? What barrel length - 610mm or 650mm? Which twist would give the maximum velocity, stabilisation and accuracy for the bullets I want to use? Can the heaviest bullets (310gn) be seated to normal length without taking up too much powder space?
A: I believe the .358 Norma Magnum is a fine, well-balanced, high performance magnum cartridge that deserves to be more popular than it is. I am a great believer in free-boring since long bullets can be seated out farther (magazine length allowing) and recommend a 650mm barrel with 1:12" twist. Case dimensions of the .338 Win. Mag. and .358 Norma are similar but the Norma has a bit more capacity and a larger bore , thus it can utilise a wider variety of powders, and with the best loads generate greater muzzle energy. For all practical purposes, with the right bullet, the .358 Norma will do nearly anything the longer .375 H&H will do and in a standard length action. The 310gn Woodleigh bullet will fulfil most hunter's needs for large African game. With the Woodleigh 250gn bullet you can get up to 2800fps with maximum loads, and 2750fps with the 275gn. There's no loads listed in the Woodleigh manual for the 310gn, but I'd guess at 2600 to 2650fps. The heaviest bullet listed in the Norma manual is 250 grains which ain't much help. The standard twist is 1:14" but 1:12" should work to advantage with the long, heavy 310 grainer.