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“To B or not to B” . . . Savage’s B.Mag, That Is

May 31, 2014
Bill Waugaman , Ohio Valley Outdoors

In January 2013, Savage introduced a completely new rifle at the SHOT show. This rifle, called the B.Mag (Bolt Magnum), was chambered in a completely new cartridge introduced by Winchester, the .17 Winchester Super Magnum. This cartridge and rifle combination brought something entirely new to the firearms industry, a rimfire cartridge capable of 3,000 fps muzzle velocity and a bolt action rifle able to shoot this new cartridge.

Two opposite trains of thought have emerged over the last year. For some, they question the value or the need for another rimfire cartridge, even with the 3,000 fps muzzle velocity. For these individuals, the .17HMR or .22WMR are just fine for a rimfire shooting; for anything more powerful, step up to any one of the many centerfire small bore cartridges. In the other camp, many individual believe the Savage B-Mag perfectly fills a void between current rimfires and small bore centerfire rifles.

* * * About the .17 Winchester Super Mag

Article Video

One misconception needs to be cleared up. The .17WSM is not just a necked down 27 caliber PAT (power actuated tooling) casing. Winchester started with the .27 PAT, but beefed up the shell case in multiple areas to ensure it can withstand the higher pressure required to produce the higher velocities of the .17 WSM. The .17WSM uses a specially blended proprietary powder and a priming mix specially formulated for this cartridge. At 33,000 psi, the pressure of the .17WSM rimfire is over 25% greater than the .17HMR rimfire and about 25% less than a centerfire .22 Hornet.

* * * About the Savage B.Mag

Even though Savage classifies the B.Mag as a 17 Series rifle, it is more of a hybrid. It has the characteristics of a rimfire rifle, but relies on the engineering savvy of the designers to build a rifle capable of handling this new cartridge.

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Savage B.Mag in .17 Winchester Super Magnum

The Barrel: The matte black barrel is made with carbon steel featuring a slender sporter taper. The barrel is threaded into the receiver to insure the proper head spacing that is critical when it comes to maximizing accuracy, just like Savage's centerfire rifles. The barrel diameter near the receiver is .86" and tapers down to barely over .5" at the muzzle, which has a rounded crown. The length of the barrel is 22" (1" longer than the other rifles in the 17 Series). The added inch helps the .17WSM attain the higher muzzle velocities. The barrel is button rifled with 6 grooves and a 1 in 9" right hand twist. The B-Mag has a raised ridge around the chamber creating clearance for the extractor, not the typical notch cut into the chamber leaving part of the chamber unsupported.

The Bolt: The new .17WSM cartridge meant designing a new bolt to meet the needed requirements. The first obvious difference is the dual rear locking lugs. As the bolt handle is turned to secure the bolt in the receiver, this rotation also compresses the bolt spring about 1/4". Hence, the stiffness in turning the bolt handle. The bolt shroud is contoured giving ample room to move the safety forward (fire) and backwards (safe) with your thumb.

Typically, rimfire firing pins are a blade that strike and crimp the edge of the casing to ignite the primer. The B.Mag has a small round firing pin that strikes the head of the cartridge about 1/32" from the outside edge (the edge of the .17WSM around the rim is the thickest part of the case).

Fact Box

For details on the .17WSM, see the article "The .17 Winchester Super Magnum...A Big Leap Forward in Rimfire Ballistics"

The bolt also incorporates a much heavier bolt spring. Again, this is a necessity created by the thickness of the casing, especially in the head, and the force needed for the firing pin to ignite the priming mix.

The Receiver: The receiver is made from carbon steel. Since there are no open sights, the B.Mag receiver is drilled/tapped and comes from the factory with scope mounts already attached. The bolt release is located on the left side of the receiver. The push of a button on the release allows the bolt to slide out easily.

The Accu-Trigger: Yes, the B.Mag is equipped with the infamous Accu-Trigger, but the design is different. The B.Mag's Accu-Trigger is adjustable from approximately 2 1/2 pounds to 4 pounds. The trigger pull can be easily adjusted by lifting and turning the adjusting screw with your fingers; no tools required.

The Rotary Magazine: A rotary magazine is something new for Savage firearms. It is a surprise from the usual stacked array. The contour of the bottom of the magazine matches the contour of the stock for a clean, smooth look. The magazine release is located in the front and has a nice, pronounced click when it seats. A guide on the back of the magazine rides in a groove to assure proper alignment and helps to secure the magazine in place. The magazine has an 8-round capacity. The cartridges do not touch each other inside the magazine. As it is loaded, each cartridge is inserted into an individual channel on the perimeter of the rotating carrier.

When you put it all together, Savage had to design and build a completely new action for the B.Mag, one that has very little in common with other rimfire platforms.

The Stock: The slender stock is made from a matte black synthetic material that is textured in the forearm and handgrip areas. The B.Mag's stock has less than 1" drop at the heel. Sling mounts are already installed at the factory. The soft rubber recoil pad is contoured to fit the shoulder comfortably. The trigger guard can easily be removed giving access to the bolts holding the stock to the receiver. With the stock removed, access is gained to the Accu-trigger adjustment.

The stock is designed to allow the barrel to be free-floating which is another way manufacturers can improve the accuracy in a rifle.

The end result for Savage is a rifle with an overall length of 40.5" and incredibly light at only 4 1/2 pounds. Depending on the rings and scope, the Savage B.Mag can weigh in less than 6 pounds.

* * * At the Range

Winchester currently manufactures the .17WSM with two different bulletsa 20 gr. polymer tip and a 25 gr. polymer tip. The 20 gr. Bullet is rated at 3,000 fps and the 25 gr. bullet is rated at 2,600 fps.

The bullet velocity was measured 10 feet from muzzle with a ProChrono Chronograph under less than favorable conditions. For a string of 10 shots, the results were as follows: 20 gr. polymer tip averaged 2932 fps (+/- 46); 25 gr. polymer tip averaged 2535 fps (+/- 36). Even though these results fell slightly under specifications, there have been numerous articles written where the actual velocities exceeded Winchester's claims.

To test the accuracy, the Savage B.Mag was equipped with a 3.5-10x50 Vortex Diamondback scope. With the nominal drop at the heel, the high-rise mounts needed for the big 50mm objective lens put the scope at a very comfortable eye level. The B.Mag was sighted in for 100 yards using the 20 gr. polymer tip cartridge. Then, both variations on the bullet weight were evaluated.

Results for ten 3-shot groups for each round were as follows. The 20 gr. polymer tip typically produced 3-shot groups ranging from .7" to 1.6". The 25 gr. polymer tip had 3-shot groups normally ranging from .8" to 1.7". While these results are not as good as others have reported with the B.Mag, they are still very respectable results for a rimfire rifle.

Using a 3-shot 20 gr. polymer tip group as a starting point, the point of impact for the 25 gr. polymer tip 3-shot group was about 1.5" lower and slightly to the right. Once you have your B-Mag zeroed, if you switch between 20 gr. and 25 gr. bullets, be sure to re-zero your scope.

The B.Mag's barrel warmed up rather quickly with repetitive shooting. 3-shot groups tended to open up as the barrel warmed up. By letting the barrel cool down between shots, the B.Mag produced the best 3-shot groups.

* * * When You Put It All Together

I have a Savage 93R17BVSS in .17HMR and a Savage 25 Lightweight Varminter in .223. Would I have a need for a B.Mag? Absolutely.

The .17WSM with a 20 gr bullet has as more energy at 200 yards than a .17HMR with a 20 gr. bullet at 75 yards. The bullet velocity at 200 yards of the .17WSM with a 20 gr. bullet is about the same as a .17HMR with a 20 gr. bullet at 50 yards. My 93R17 is a deadly groundhog rifle, but I limit my shooting to 100-125 yards or less. For longer shots, my Model 25 is used. I see the Savage B-Mag as an effective groundhog rifle for shots out to 200 yards.

For hunting groundhogs or coyotes, the boom of a centerfire rifle can be disturbing to nearby homes. The quieter crack of a rimfire rifle is more acceptable. The .17 WSM in a B.Mag gives you the advantage of longer range and more energy in a rimfire without the muzzle blast of a centerfire. Plus, .17 WSM ammunition is about to 1/3 the price of centerfire hunting ammunition.

Probably the best utilization of a Savage B.Mag in .17 WSM would be as a youth's varmint rifle. This rifle is light weight, has minimal recoil, has less muzzle blast than a centerfire, gives substantially better ballistics than any other rimfire, is effective out to 200 yards, ammunition is only about 30 cents per round, and with an MSRP of $349 for the Savage B.Mag, you're not investing a lot of money.

Are there some things I don't like about the new B.Mag? Yes, but they're more of personal preferences than functionality. I commend Savage for doing an outstanding job of bringing this new cartridge from Winchester to market in a rifle that had to be built almost from scratch, and still maintain an affordable price.



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