.358 WSSM

Like many states in the region, Indiana has not allowed deer hunting with rifles.  Shotguns, handguns, muzzle-loaders, and bows are allowed.  Some say this is intended to make the hunt more challenging, thereby promoting growth in the deer population (particularly several decades ago when deer populations were low).  Others say it is intended to limit the range of a potential stray bullet.  Whatever the case, a traditional deer hunting rifle could not be used in Indiana to hunt deer.  However, in 2007, Indiana loosened the restriction slightly by allowing rifles that fire pistol calibers.  The Indiana DNR defines pistol calibers as having a minimum bullet diameter of .357″, a minimum case length of 1.160″, and a maximum case length of 1.625″.  The intent was to allow rifles that fire cartridges like the .357 Magnum and the .44 Magnum.  (Note that this year, the maximum case length has been increased to 1.800″.)

However, wildcatters immediately conceived of the .358 WSSM.  It is based on the (ill-fated) Winchester Super Short Magnum case, necked up for a .358″ bullet. The resulting cartridge duplicates or exceeds the performance of the respected .358 Winchester.  The Indiana DNR has become aware of these wildcats and gone along with them.  Consequently, the .358 WSSM has become one of the most effective calibers allowed for deer in that state, and there has been a surge of interest in this and similar wildcats.

One of the best ways to have a .358 WSSM rifle built is to buy a rifle chambered in a standard WSSM caliber and have it re-barreled.  Winchester and Browning, during the short time that they were making WSSM rifles, produced a special “super short” rifle action, and this action is the most likely to reliably feed the short, fat WSSM cartridges.  Last year, I bought a Browning A-Bolt Hunter in .223 WSSM for this purpose.  At that time, a few WSSM rifles were still sitting on dealers’ shelves, and they were anxious to get rid of them.  I acquired one via GunBroker at a very good price.  I put a new barrel on order with the gunsmith and shot the rifle a few times while I waited.

(For anyone who wants to know, the .223 WSSM is quite loud and has a surprising amount of recoil for such a small bullet.  It was quite accurate with factory ammunition, and I even had the opportunity to kill a groundhog with the rifle before sending it in to the gunsmith to be converted.)

Early this year,  the gunsmith received the barrel, and I sent the rifle in for its work.  It came back to me in early May, and I am extremely pleased with the results.  It came back with a 23″ barrel.  I love the balance of the rifle, and it is quite light.  The gunsmith re-worked the trigger, and it is crisp and light (perhaps too light).  He modified the feed ramp, which greatly improved the feeding of cartridges.  The workmanship of the barrel and the modification of the stock is top notch.

As a wildcat cartridge, I cannot buy factory made ammunition.  I have to handload the ammunition using cases formed from another cartridge.  The most time-consuming step is forming the brass, but once that has been done, I can use the case multiple times.  I am following a regiment that was recommended by someone else who has experience with this cartridge.  I start with .25 WSSM brass, anneal the neck, expand to .30 caliber, anneal the neck again, expand to .35 caliber, and anneal the neck a third time.  I have found that it will be necessary to turn the necks, since I have a somewhat tight necked chamber.

Unfortunately, the neck turning tool I already had does not handle .358″ diameters.  The one I really wanted was on backorder  for two months.  I finally received the tool and was able to load up a batch of ammunition.  More than a year after starting this project, I was finally able to shoot my rifle.

The ballistic performance and recoil of this round easily exceeds that of the .30-06 Springfield.  Using VihtaVuori N-135 with 180 grain bullets, I achieved over 2850 fps without ever really seeing signs of excess pressure.  With 225 grain bullets, I tested as high as 2600 fps, but settled on a load right at 2500 fps.  This puts the performance of the cartridge firmly between the .358 Winchester and the .35 Whelen.

I had hoped to develop a load for whitetail deer using the 180 grain Speer flat-nose bullet, which was the only 180 grain bullet at the time designed to withstand the velocities I was expecting.  (Barnes has just released a 180 grain T-TSX bullet which is sure to hold up to those velocities, and I intend to give it a try.)  However, the Speer bullet gave me disappointing accuracy, around 3 MOA.  I switched to my second choice, the 225 grain Sierra GameKing, and the results have been astounding.  It is a great bullet, accurate, and designed for .35 Whelen velocities, but it produces more recoil than I need.  Experimenting with different charges, bad groups were less than 2 MOA, and good groups were sub-MOA.  The gunsmith says he cut the throat specifically for this bullet.  My better groups were mostly vertical, which suggests that I need to develop more consistent shoulder pressure.

The Missouri firearms deer season was quickly approaching, so I selected a sub-MOA charge and zeroed the scope for it.  Unfortunately, I never got to take a shot at a deer with it.  Maybe next season, and maybe it will be in Indiana.

Update 2017: I finally managed to take a deer with this rifle.  I can’t say anything meaningful about the terminal performance, because it was a heart shot at 30 yards.  The doe left a Quentin Tarantino blood trail.  Now that I have successfully taken game with the rifle, I want to chip out the bedding material the gunsmith used to make it not free-floating.  The vertical stringing must be due to that.  I will have to start over with load development, so I will work on a load using H4895, which is said to be the most accurate for this cartridge and is good for a little more velocity.