Fastest Rimfire Ever: .17 WSM!

By Glen Wunderlich

Charter Member Professional Outdoor Media

Illustration courtesy of Winchester Ammunition

About seven years ago, a new .17 caliber rimfire cartridge was developed and it seemed to be the perfect solution for nighttime varmint hunters:  the .17 Winchester Super Magnum (WSM).  Back then, Michigan hunters’ choices were limited to shotgun and rimfire ammunition for night use.  Shotguns are fine for close-up work, but the rimfire choices were on the anemic side.

With the advent of the new .17 caliber firecracker, Michiganders took to it like “free” money from government.  Touted as the world’s fastest rimfire, it would propel a 20-grain projectile at an unheard of velocity of 3000 feet per second (fps).  Such speed put it in the realm of some high-stepping centerfire options, but with ammo at a fraction of the cost.

However, Winchester’s debut of this speedster was not without issues.  I had spent hours weighing each cartridge and grouping them according to results in an effort to squeeze the most accuracy from the factory fodder.  However, I discovered that the ammo had obvious factory defects in the brass cases.

Couple that with a new firearm design by Savage, known as the B-Mag and questionable barrel twist rates, Michiganders became disenchanted with the latest and greatest rimfire offering.  Savage began replacing barrels for customers and I pushed it aside out of frustration.  By the time ammunition and firearm concerns were resolved, Michigan lawmakers changed its night-hunting regulations to allow certain centerfire calibers for night use.

In the meantime, I had obtained a laminated stock from Boyd’s

Savage B-Mag, Boyd’s Laminated Thumbhole Stock, Nikon Coyote Special Scope

(www.boydsgunstocks.com) and installed a suitable Nikon scope on the rig.  In addition, another zippy ammo offering was introduced by Winchester in a tiny 15-grain, non-lead configuration and it became time to give it another go.

The new, lighter bullet ammo increased muzzle velocity to an astounding 3300 fps and it was producing some surprisingly good results on paper targets.  This comes from ammo that is priced at approximately $16 per box of 50 cartridges, which is less than 20 rounds of centerfire ammo.  Even though I handload ammunition, I can’t do it for less.  In fact, MidwayUSA.com has it in stock right now for the ridiculous price of $9.36/Box of 50!

Although the necessity of using rimfire calibers exclusively for night hunting has been negated by Michigan’s updated regulations, the diminutive round still has a place for economically minded shooters.  However, it may take some range time to determine which of the ammunition offerings will produce the best and acceptable accuracy.

I’ve settled on the light 15-grain loads from Winchester.  And, if you think such a small bullet wouldn’t take out a mouse, I’ve learned better.  Just for fun, I set up some expired canned goods at various ranges to see what kind of mess I could make; the results were explosive!

Since then, I’ve taken a few problematic woodchucks from the gene pool with the 15-grainers and when the trigger was pulled, it was like the rodents blew fuses.  Nobody could ask for more humane results.

Taken at 82 yards with the 15-grain Winchester ammo

If you are looking for an inexpensive, yet totally capable caliber to use for rodents around the homestead or across a field, many options exist in firearms and ammunition in .17 WSM.  And, even though hoarders are making some ammo hard to get, this caliber is still readily available and a great value.  Plus, it’s a heck of a lot of fun and economical at the same time.