Neck down a .270-diameter, concrete-nail-driving industrial rimfire blank to accept a .17-caliber jacketed bullet and what do you get? The fastest rimfire cartridge in the world, that’s what. Combine that with a lightweight, quick-handling bolt action of completely fresh engineering and you end up with what could be the ultimate 200-yard varmint and small-game rifle.
Winchester Ammunition and Savage Arms have done just that. You’ve likely caught wind of the blistering .17 Winchester Super Magnum (WSM) rimfire cartridge—it shoots a 20-grain, polymer-tipped projectile at over 3,000 fps—that has been making ripples across the shooting community. Bigger in body than other current rimfire cartridges, it doesn’t fit in popular rimfire actions.
Working together with Winchester, Savage Arms engineered the sleek, new caliber-specific B-MAG action for the .17 WSM. It’s just as extraordinary as the new cartridge it houses. Shooting Times managed to obtain one of the first production samples to come off the line. Here’s a close look at it.
All-New, Cartridge-Specific Design
Weighing in at less than 5 pounds, it has a 22-inch, matte-blued barrel that is press fitted into the front of a unique action and secured with setscrews. Not quite like a Ruger 10/22, but in the same spirit. Measuring 0.525 inch at the muzzle and 0.650 inch 4 inches in front of the receiver, it’s a slender, very lightweight stalking-type barrel contour.
The bolt has dual, opposing rear locking lugs; a rocking, plunger/spring powered extractor; and a plunger-type ejector. Unlike many rimfire bolts that are flat across the face, this one encloses the base of the .17 WSM cartridge on three sides, open only on the bottom, and is of nonrotating design. In a departure from typical engineering, it is a cock-on-close bolt, and only the bolt handle, racy-looking shroud, and locking lugs rotate.
Typical rimfire firing pin springs have to be strong to crush the folded rim of a cartridge case and detonate the impact-sensitive priming element inside, and the massive, thick rim of the .17 WSM requires a very strong firing pin spring to ensure reliable detonation. As the bolt handle and locking lugs are rotated into battery, an angled slot cams a pin forward, compressing the firing pin spring from the rear. According to Savage’s Bill Dermody, the system acts in similar fashion to the cams on a compound bow, enabling the shooter to easily cock the piece.
A classic, rocking-type bolt release lever is on the left side of the action, which allows the bolt to be withdrawn easily for cleaning or whatnot. It’s a welcome departure from the multiple-finger-required, contortionist bolt release system on typical Savage centerfire rifles.
To help shooters milk the best accuracy possible out of their B-MAG rifles, Savage specced the model with the AccuTrigger. As most shooters know by now, the Accu-Trigger is a light, crisp, two-stage design that houses a safety lever within the trigger shoe, helping reduce negligent discharges and, specifically, accidental detonations from violent blows—for example, if dropped. From the factory, the B-MAG’s AccuTrigger measured an average of 2 pounds, 4 ounces, with a variation of less than 4 ounces over a sequence of five measurements. Delightful.
A tang safety resides at the rear of the bolt shroud and is actually incorporated into the rear of the AccuTrigger housing. Forward for “Fire” and rearward for “Safe.” A small red “danger dot” shows when the safety is disengaged.
In a notable departure from conventional current Savage design, engineers went with a rotating, detachable magazine. Containing eight rounds, it clicks smartly into place and is removed via a plastic latch at the forward end of the magazine, which is integral to the glass-filled nylon magazine body.
The “bottom metal” trigger guard and magazine housing is also made of glass-filled nylon, like the stock and magazine body, and is held in place by a tab at one end, which fits into a mortise in the stock, and a latch at the other. Similar to the magazine, the latch is integral to the housing, but is hidden within the magazine well and can be released only with a screwdriver or other tool.
In order to access the action bolts and remove the barreled action from the stock (the only reason I can think of to do this would be to adjust the AccuTrigger, and it’s tuned pretty well from the factory), the nylon trigger guard and magazine housing must be removed. Take the magazine out and stand the rifle on its muzzle on a piece of cardboard or whatnot to protect it. A yellow dot can be seen at the inside front of the magazine well. Press gently on it with a screwdriver and lift on the trigger guard. The housing will pop out, allowing access to the two captured Torx screws that secure the action to the stock.
The B-MAG’s stock reminds me of the Savage Axis stock; it’s slender, ergonomic, and aesthetically proportioned. Panels reminiscent of molded-in stippling at the grip and fore-end provide gripping texture, and proper metal sling-swivel studs are found fore and aft. The buttpad is thin—no real recoil being present to necessitate a cushy pad—but is of slip-reducing rubber, minimizing the chance that your leaned-in-the-kitchen-corner skunk-getter will come clattering to the floor when the cat brushes against it in the wee hours of the night.
In keeping with classic rimfire versatility, I would like to see iron sights on the B-MAG. There are none, and it’s not hard to figure out why. It really takes a magnified optic to tap into the potential of the .17 WSM cartridge, so Savage opted out of the irons. On the plus side, Weaver rail-type scope bases come factory-mounted on the B-MAG. I mounted a new Burris 4.5-14X 42mm C4 scope (see the accompanying sidebar) for accuracy testing.
In the Field
Old-fashioned bore sighting—peering through the tiny .17-caliber bore—got me on paper at 100 yards, and with a slight windage and elevation adjustment, I was soon shooting nicely centered five-shot groups. Right from the start the rifle preferred the 20-grain projectile, averaging right at 1 MOA. The 20-percent heavier 25-grainer turned in more consistent standard deviation and extreme spread numbers, but just didn’t group as well. Unfortunately, I had only two of the three Winchester loads available; I lacked the 20-grain hollowpoint Super-X load.
In a pleasant turn of events, the two Winchester loads I did test gave chronographed velocities slightly above factory ratings: 3,017 fps for the lighter bullet and 2,633 fps for the heavier one. The high (for .17 caliber) ballistic coefficients of these two bullets (.185 for the 20-grain version and .230 for the 25-grainer) enables them to hold on to energy better than any other cartridge in its class, including the .22 Hornet, which it outperforms as distances stretch. The .17 WSM even nips at the heels of Hornady’s new centerfire .17 Hornet out to 200 yards or so.
I did experience a couple of functional issues while shooting. Some 28 rounds into my accuracy testing, a burr apparently left on the tip of the extractor while machining rolled below the tip and prevented the extractor from engaging the rim of a cartridge. I completed my accuracy testing by dropping the magazine after every shot and removing the spent case with my fingernail. The burr was easily removed by careful use of a needle file when I returned home, and the extractor once again heaved the empties out and aside with perfect reliability.
Shortly after the extractor hiccupped, the rotary magazine went awry. Though still partially loaded, the follower failed to roll the remaining fresh rounds up to feeding position. Being something of a gunsmith, I had my tool kit along, and a careful dissection of the magazine revealed that the preloaded follower spring had slipped and the follower no longer had any tension. Two minutes later I had engaged each end of the coil spring in the appropriate slot, rotated the magazine end plate into position, loading the follower spring by doing so, and replaced the two screws that hold the assembly together.
I haven’t had a problem with either the extractor or the magazine since. The issues were minor, but could have required returning the gun to the dealer for inspection and either remedial gunsmithing or a return to the factory. On the other hand, most gun guys are handy with tools and could have accomplished the fixes I performed each in just a couple of minutes.
When I picked up the gun—a writer’s sample on loan—I had to pry it away from the guys at Gunnies Sporting Goods in Orem, Utah, the FFL dealer I transfer guns through. Luckily, I had time to spare, as the rifle got passed around between most of the guys behind the counter before I managed to escape with it.
The rifle handles well; carries comfortably in the hand; and shoulders, points, and balances quite nicely. Recoil is very civilized, allowing the shooter to spot impacts through the scope with ease, and it’s quiet in a non-neighborhood-disturbing way. I can think of no better rig for stalking Eastern groundhogs in the hedgerows, Western pot-gut gophers, or river-going nutria in the Northeast.
I’m more excited about the B-MAG rifle—and the cartridge it houses—than I have been over any new Savage rifle in many years. It’s different, it’s innovative, it’s pleasant to shoot, and it’s a very capable deterrent to furry nuisances. At less than $350 and chambered for a fairly inexpensive cartridge that outperforms anything short of hot centerfire .17s, it deserves a place on the gun rack of every serious varmint shooter.