By Jason Brooks, WHJ Field Editor

Kimber firearms are known for their extremely lightweight and accurate rifles. Machined to tight tolerances, assembled and completely built in the U.S.A. their rifles are carried into the backcountry each fall by hunters who want a rifle that shoots well but doesn’t weigh down the pack. The company was founded in 1979 and has added to the line-up of both rifles and handguns as the company’s reputation for bench rest accuracy, comfort, and quality construction of their firearms became an industry leader. For 2019 they added just one rifle to their line by updating one of the most popular models the Mountain Ascent in the new Mountain Ascent Subalpine. I have a Kimber Mountain Ascent Moss Green in the .280 Ackley Improved and have hunted both the Washington and Idaho backcountry and this rifle has taken several elk and mule deer. So, when I got the chance to put the new Kimber Mountain Ascent Subalpine to the test I chose to go with a short action caliber and the .300WSM was an obvious choice for me as an elk hunter who also pursues black bear and mule deer.

Design and Features of the Kimber Mountain Ascent Subalpine

Action: The rifle is an 84M bolt action that has tight tolerances and virtually no “slop” when you lift the skeletonized bolt knob. It has a Mauser claw extractor and a 3-position Model 70 style safety. Sliding the spiral bolt both backwards and forwards is smooth with virtually no lateral movement. The design of the bolt is to reduce weight, in fact, everything about this rifle is designed to reduce weight but keep the machined accuracy of the rifle to its fullest potential. At the top of the action are pre-drilled and tapped holes to mount the scope bases. The Kimber Mountain Ascent Subalpine I was sent came with a set of one-piece Talley rings and bases. Again, saving weight but more importantly it keeps the scope securely mounted on the rifle since the light weight can increase vibration in mounting screws. 

Barrel: The magnum calibers sport a 26-inch barrel and the .280 Ackley Improved comes with a 24-inch barrel. The .30-06 and .308 have a 22-inch barrel. All of the barrels are “pencil” thin and have a quarter length flute on them that helps keep the barrel “stiff” as well as reduce weight. All of the rifles also come with a muzzle brake that is threaded on and a thread protector if you choose to remove the break. For me, the muzzle brake is a must when it comes to a super-lightweight rifle in a magnum caliber. The barrel is mounted with a pillar block that helps accuracy and is guaranteed to have a sub-MOA right out of the box. 

Stock: The stock is reinforced carbon fiber and new for 2019’s Mountain Ascent Subalpine is the Gore© Optifade© Subalpine pattern. This provides a soft touch that almost warms as you hold the rifle and made it very comfortable to grip. It also tends to be “non-slip” which helps when you use a rest to shoot the rifle as it grips the rifle and helps you hold it steady. The rifle also comes with a 1-inch recoil pad and the total length of pull is 13.8 inches. 

Trigger: When it comes to shooting a lightweight rifle accurately one of the most influential factors is the trigger. Since the rifle is so light any pressure on the rifles causes it to move and that decreases accuracy. Kimber knows this which is why the factory trigger is adjustable. The assembly is easily removed and two set screws adjust the length of travel and the pull weight. When you get the rifle from the factory it comes with the trigger pull set to between 3.5-4 pounds and no travel in the trigger. You can adjust this yourself if you feel the need but be sure to stay within recommended tolerances. A quarter- to half-turn on the set screw will lighten the trigger significantly but I found on this rifle that this was not necessary. 

Safety: Kimber uses a 3-position Model 70 style safety. The safety locks forward once the rifle is fired which is a reminder that the rifle has a spent case in the chamber. The 3 positions allow you to keep the rifle in the “safe” position and able to work the bolt to unload the rifle’s internal magazine. It has a fairly large flange that is textured and is easy to use even when wearing thick gloves. 

Magazine: Currently the Mountain Ascent Subalpine has an internal magazine which cuts down on weight. Loading the magazine is easy to do in the short action of the .300 WSM and the rifle holds four cartridges. In the long action that I have in .280 Ackley Improved I have found that the last round can be harder to load and has caused some feeding problems. The .300 WSM was prone to feeding problems in other models by different manufacturers early on and is one reason why it is still not as popular as some of the other “wildcat to mainstream” calibers. Kimber has done a good job in overcoming the feeding issues of the short, fat casing built off of the .404 Jeffery that the .300 WSM uses. The rifle cycled each round easily. 

Muzzle brake: Thankfully Kimber has made the muzzle brake part of the package instead of an “add on.” This is an extremely lightweight rifle and the recoil of the .300 WSM is not fun to shoot. But the muzzle brake takes a lot of the “felt recoil” out of the rifle. It does add to the increased noise and hearing protection is a must, even when hunting. If you decide you don’t want to use the muzzle brake then you can simply unscrew it from the end of the barrel and put on the thread protector that is included. When I shot the .300 WSM for the first time I was expecting it to hit me back pretty hard but was surprised at how well the break worked. In my opinion the rifle feels much like a .30-06 when fired which I can shoot at the range at afield without worry. 

Performance and Accuracy: Testing the Kimber Mountain Ascent Subalpine

Performance: When it comes to the Kimber Mountain Ascent Subalpine, it is made to be carried easily afield. One of the main differences between the Kimber rifles and the other rifles I own that are sub-6 pounds is the accuracy and increased ballistics. The extremely long barrel Kimber offers for such a light rifle in a magnum caliber allows the use of the .300 WSM full potential. The length of the barrel reduces pressure build up. As a cartridge is fired and the powder burns it creates an increased pressure of gasses that pushes the bullet down the barrel. Once the bullet leaves the barrel it is no longer being pushed. The more travel or time the bullet is in the barrel the faster the bullet accelerates which means the long barrel increases the bullet speed compared to a shorter barrel. With very tight machined tolerances, the long barrel, quality trigger, and pillar bedding the Kimber Mountain Ascent is guaranteed sub-MOA accuracy with quality commercial ammo. They even test fire it at the factory before sending you the rifle to confirm it is accurate.  

The Test: Just like any new rifle the first thing I do is clean it. Remove the bolt and wipe it down with a solvent, along with running a few patches down the barrel and work the action once it is all assembled. This is an operational function testing to make sure everything is in working order. The rifle was then fitted with the supplied Talley rings that have the bases integrated into them with the screws having some thread lock applied. Four cartridges load into the internal magazine and from there the rifle was rested on a shooting rest. The trigger didn’t need any adjusting and the rifle fired without issue. Cycling the fat and short .300 WSM was relatively easy with no feeding problems occurring. Accuracy off of a bench was extremely accurate. Replicating these conditions during hunting is impossible but knowing the rifle shoots tight groups means that if I miss then it is my fault and nothing to do with the rifle. 

Bottom Line: Kimber makes high quality firearms and the Mountain Ascent Subalpine exceeds even their great gun making standards. Kimber runs each rifle through tight tolerance inspections and it shows. An extremely light weight rifle that is designed to maximize the cartridge chambering to its fullest potential it will be hard to beat the Mountain Ascent Subalpine for a backcountry hunt. The rifle will not make a good Whitetail “deer drive” gun as it should be fired from a steady rest. And if you take the time to set up for the shot you will know that the rifle is more than capable of making it count. For the backcountry hunter this is one of the best, and is the lightest magnum caliber rifles on the market today.  

Sidebar: quick facts:

Model:Mountain Ascent Subalpine

Manufacturer: Kimber

Action: Type: 84M; Stainless steel; 3-position Model 70-type wing safety; Mauser claw extractor; Front locking repeater

Magazine capacity: 4

Offerings: .308, .30-06, .280 Ackley Improved, .300 Winchester Magnum, .300 WSM

Tested: .300WSM

Scope Used in Test: Leupold VX-3i in 4.5-14×40

Stock: Reinforced carbon fiber 

Recoil pad: 1”

Length of pull (inches): 13.75”

Drop at heel (inches): 0.54”

Drop at comb (inches):0.43”

Barrel: 22” stainless steel, satin finish; Sporter contour, 1:10 Twist (rh); 4 grooves; 

Muzzle brake and thread protector 

Overall length: 41 ¼” 

Weight (no scope): 4 lb., 13 oz.

Length of pull: 13.8”

Trigger: Adjustable

Trigger pull weight: Factory, 3.5-4 lb.

Sights/scope Mounts: None; drilled and tapped for mounts.

MSRP: $2,040