358Shooting Times Alaska
The 358 STA was created by necking up the 8mm Remington Magnum case to 35 caliber. Although A-Square has made brass and loaded rounds, the 358 STA is primarily considered to be a "wildcat" cartridge. After Layne Simpson initially started messing with the idea in 1990, it was later decided to straighten out the case a little to add more powder capacity. Case body diameter at the location where the shoulder begins was increased from 0.487" to 0.502". Make no mistake; this round is a real bad boy, capable of taking any game in the world. It drives 250-grain bullets at nearly 3000 fps, a good 150 fps faster than the already very capable 358 Norma Magnum.
On the upper end of things, there are some pretty good bullets made for the super-powerful 35s. Woodleigh goes clear up to 310 grains, both soft point and solid, and Swift has that wonderful 280-grain A-Frame that shoots sub-moa in my Ed Brown 358 Norma Magnum with the Pac-Nor 12-twist barrel.
In recent months, I have talked with Cooper Arms about the possibility of adding the 358 STA to their available chambers for the Model 52. In the synthetic-stocked Excalibur, this would be a fairly light rifle with considerable recoil. I already have one of these rifles chambered for the 8mm Remington, as well as the 7mm STW, and this would complete the set of three. A barrel large enough in diameter to handle the 416 Remington Magnum, the other well-known cartridge based off of the 8mm Remington Magnum, would not be possible in the Excalibur stock.
Despite the fact that the 358 STA is powerful enough to stop Cape buffalo, African lion, and African elephant, it is not of legal bore diameter in most countries for dangerous game. That has limited its use, and therefore the number of rifles being made for it.
I had the opportunity to fire a sporting rifle in 358 STA that I would guess weighed in at around 8-1/2 pounds. The recoil immediately reminded me of my Browning X-Bolt Stainless Stalker in 375 H&H; not something that you would enjoy shooting very many times on any given day. The round was the 280-grain A-Square Lion Load at 2750 fps. The bullet is designed to break up quickly rather than hold together on lion, thereby causing severe damage instantly and stopping the beast in its tracks.
The owner of the 358 STA claimed that the cartridge is very flexible when it comes to accepting a wide variety of loads at several power levels. In fact, he loads it down considerably and uses the Sierra 225-grain SBT on deer in Wisconsin with excellent results, including less meat damage than a 270. That load is about mid-power for a 35 Whelen. Of course, that same bullet can be driven at over 3000 fps if you really want to make a splash.
If Cooper adds the 358 STA to its already long list of cartridges for which they chamber, we'll post it right here at the Northwest Magnum site. And, of course, you're welcome to use us as your Cooper supplier. We're on the same highway, separated by only about 115 miles and a state line, and have a wonderful relationship with them. We have already shipped Coopers to many states, and every customer so far, whether a walk-in or at a distant location, has been overwhelmingly satisfied. Many are now repeat customers. Call us when you're ready, or even if you just want to discuss the possibility.