August 06, 2021
Although various forms of the design have been fielded for nearly 150 years in other countries, the straight-pull bolt-action rifle has largely been ignored by hunters in the United States.
We're used to lifting the handle before cycling the bolt and pushing it back down at the end of the cycle. That's just the way a bolt-action rifle works, right? Well, it doesn't have to.
A straight-pull bolt need not be rotated to move lugs in and out of recesses during cycling; just pull the handle straight backward to remove the bolt from battery, and push it directly forward to achieve lockup.
The primary benefit of a straight-pull rifle is speed in cycling because the system eliminates two steps in the process. Plus, all the movement stays in one plane parallel to the bore.
Savage Arms delivers these advantages in its new Impulse, a rifle designed with an eye on American trends yet engineered to raise in-the-field performance to another level.
Straight Pull with Hexlock Bolt
The key to the Impulse's straight-pull action is Savage's Hexlock bolt, which relies on six ball bearings encircling the bolt head, rather than square-shouldered lugs, for lockup. When the Impulse's bolt handle is pushed fully forward and the bolt is closed, a plunger inside the bolt body forces the ball bearings outward. The bearings lock into a recess machined in the barrel extension.
When a round is fired and pressure against the bolt head increases, the bearings tighten to provide greater lockup strength for safety. Savage tested the Hexlock bolt with magnum and high-pressure cartridges, and it is capable of handling both. After the pressure subsides, pulling back on the bolt handle causes the interior plunger to recede and release the ball bearings from their recess, enabling the bolt to travel to the rear and eject the case.
A series of cams inside the bolt body near the root of the bolt handle controls the movement of the plunger. These cams are actuated by the back-and-forth movement of the handle, keeping all the motion needed to cycle the bolt in a straight line. The bolt handle does rotate, but its rotation is in a plane parallel to the receiver and the bore instead of roughly perpendicular to it, as with conventional turn-bolt actions. The Impulse's rotary bolt handle works with the cam system to provide a mechanical advantage during cycling.
Because of this rotation, the bolt handle can be placed in five different positions that change its angle relative to the shooter. The bolt handle can also be moved to the left side of the gun in about a minute with no special tools required.
Although Savage currently offers Impulse rifles with the ejection port on the right side only, left-handed shooters nonetheless get a rifle that they can set up to cycle with their dominant hand, without having to reach over the stock.
At the back of the bolt is a large rectangular button that, when pressed, unlocks the bolt handle to allow the ejection of a live round. The two-position tang safety can remain engaged during this process.
The bolt feeds from a single-stack, detachable box magazine. Chambered in 6.5 Creedmoor, the Impulse I tested has a magazine that holds four rounds. It audibly clicks into place, and it drops free when I pull the latch to release it without hanging up. The magazine fits nearly flush with the bottom of the stock, and its slightly rounded base matches the stock's contour for comfortable carry.
Since the HexLock bolt locks up with the rifle’s steel barrel extension, Savage is able to machine the Impulse's receiver from aluminum. This reduces weight, and the company takes further advantage of the material by machining an integral Picatinny rail with a 20-MOA cant into the receiver. All you need to mount a scope is rings, and the length of the rail provides abundant options for positioning an optic for proper eye relief.
The barrel extension is clamped to the receiver and secured by four bolts. Headspace between the chamber and the bolt face is set with Savage's proven barrel-nut system, with the recoil lug sandwiched between the receiver and the locking nut. The arrangement permits an Impulse receiver to accept different barrels, which complements the bolt's ability to be fitted with interchangeable bolt heads for converting the rifle to fire a range of cartridges.
Savage Impulse Big Game Specifications
- Type: straight-pull, bolt-action centerfire rifle
- Caliber: 6.5 Creedmoor (tested)
- Magazine: detachable box; 4-round capacity
- Barrel: 22 inches, medium contour, fluted; 1:8-inch twist; muzzle threaded 5/8x24
- Trigger: user-adjustable AccuTrigger
- Stock: synthetic AccuStock with AccuFit, adjustable for length of pull and comb height
- Sights: none; 20-MOA Picatinny rail integral to the receiver
- Finish: hazel green Cerakote receiver and barrel; KUIU Verde 2.0 stock
- Overall Length: 43 1/2 inches
- Weight: 8.8 pounds
- MSRP: $1,449 (savagearms.com)
A Better Fit
The Impulse Big Game variant I tested has a 22-inch, medium-contour barrel, which is fluted to further reduce weight. Its muzzle has 5/8-24 threads for accepting a suppressor, and it comes with a cap. Like the receiver, the barrel is finished in a muted, hazel green Cerakote to resist corrosion and abrasion.
To enhance accuracy, the barreled action is mated to a rigid aluminum chassis embedded inside the synthetic stock. Savage calls it the AccuStock, and it surrounds the bottom of the receiver along its entire length to provide a stable bedding platform.
A steel block inside the chassis contacts the recoil lug, and as the action screws are tightened, the receiver is drawn into the chassis with even pressure along its length and sides. Pressure and contact between the barreled action and the chassis remain consistent despite changes in heat and torque acting on the stock.
The buttstock features Savage's AccuFit system, which permits shooters to change both length of pull and comb height to suit individual builds and optic positions. Length of pull is adjustable in 1/4-inch increments with four included inserts that fit between the end of the buttstock and and recoil pad.
Comb height can be altered in 1/8-inch increments through the use of five different riser inserts. You'll shoot a rifle that fits you better than one you have to adjust your body to, and it's worth taking advantage of the adjustments provided by the AccuFit stock. The stock also includes soft-touch panels in the grip and fore-end to aid purchase. It's finished in KUIU's Verde 2.0 pattern.
Load: Federal Ammunition 140-grain Fusion
- Average Muzzle Velocity: 2,692 fps
- Smallest Group: 1.02 inches
- Largest Group: 1.22 inches
- Average Group: 1.14 inches
Load: Hornady Precision Hunter 143-grain ELD-X
- Average Muzzle Velocity: 2,618 fps
- Smallest Group: .58 inch
- Largest Group: 1.07 inches
- Average Group: .79 inch
Load: Norma Dedicated Hunting 143-grain BondStrike Extreme
- Average Muzzle Velocity: 2,657 fps
- Smallest Group: .63 inch
- Largest Group: .91 inch
- Average Group: .70 inch
Velocity is the average of 10 consecutive shots measured with an RCBS AmmoMaster chronograph. Accuracy obtained by firing five, three-shot groups at 100 yards from a sandbag rest.
Faster and Accurate
Of course, Savage gives the Impulse its popular user-adjustable AccuTrigger. This feature may do as much for the rifle’s accuracy—or at least a shooter's ability to exploit that accuracy—as the AccuStock and AccuFit systems.
During testing, I immediately noticed the straight-pull Impulse was faster to cycle than a typical turn-bolt rifle. The bolt came back and moved forward efficiently and smoothly. Not only did this increase the cycle speed, it also helped me keep the rifle steadier and on target while running the bolt. I experienced no failures to feed or eject during range sessions that totaled about 140 rounds.
Accuracy, too, was on par with what I've come to expect from Savage rifles. That is to say it was excellent. The Impulse was a solid sub-MOA shooter with two of the factory loads I tested for accuracy, and it wasn't far off that mark with the third.
Savage has never been afraid to be bold in introducing new technologies, and the company has a successful track record with its innovations. (Take the AccuTrigger as an example.) The American-made Impulse may come as a surprise to hunters in the United States, but I don't think it will be difficult for them to recognize and accept its benefits.