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A Flawless Flyweight: Kimber Model 84M Mountain Ascent Review

by Layne Simpson   |  December 18th, 2012 12
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Kimber’s new Model 84M Mountain Ascent rifle weighs just 4 pounds, 13 ounces. With the Leupold Vari-X III 2.5-8X scope (11.4 ounces) and the lightweight Talley mounts and rings (2.2 ounces) installed, the complete rig totals 5.67 pounds.

The Kimber Model 84M and I go back to almost its beginning. In 2002 I took one of only two preproduction rifles in existence at the time to New Zealand where I used it to bag a magnificent free-ranging red stag. During that same hunt I also took very nice fallow and sika deer. Both the rifle and I proved to be accurate enough. For the trip I packed 40 rounds of .308 Winchester ammo, used five in confirming the rifle’s zero when I got there, fired three at game, and left 32 rounds with the outfitter. I have since tried other Kimber rifles in other calibers, and while all were quite nice, to this day the Model 84M in .308 is my pick of the entire litter.

The rifle I hunted with had a walnut stock and weighed a bit less than 6 pounds without a scope. That was light then, and it still is, but at 4 pounds, 13 ounces, Kimber’s new Mountain Ascent version of the Model 84M reduces the hunter’s load by a good pound. It is presently available only in .308 Winchester with a 22-inch barrel, but I won’t be surprised to see the 7mm-08 Remington become available sometime in the future. A second variation built on the longer Model 84L action and slated for availability in .270 Winchester, .280 Ackley Improved, and .30-06 Springfield will be a half-pound heavier. Most of the additional weight is in its longer action, but two more inches of barrel along with lengthening the stock in the action area add a bit as well.

Worth Hocking the Farm For
Some of those ounces were trimmed away by utilizing a trim yet grown-up-sized stock made of Kevlar-reinforced carbon fiber weighing only 20 ounces. Its 3/4-inch-thick pad is quite effective at soaking up recoil, and as any hunting rifle should, the stock has posts fore and aft for quick-detach sling swivels.

The finish on the stock is described by Kimber as Gore Optifade Open Country Concealment. Regardless of whether you are hunting in dry desert, frigid arctic, or rocky high country, it will hide from sharp-eyed game animals, yet it is sure to get plenty of attention in any hunting camp. My wife Phyllis absolutely loved the stock at first sight, but there are likely those who won’t. For them, the stock of Kimber’s Montana has a more conservative finish, and it weighs only 5 ounces more. As for me, I am so impressed by the Mountain Ascent that zebra stripes or even scantily clad mermaids would be just fine.

Weight was further reduced by the use of a blind magazine rather than the more commonly seen hinged floorplate. This was an especially practical design option for Kimber engineers since placing the Model 70-style, three-position safety in its mid-engaged position unlocks the bolt for safely unloading the magazine by cycling cartridges through the action.

The internal steel magazine box holds four rounds, and with a length of 2.820 inches, it is 0.010 inch longer than SAAMI maximum for the .308 Win. cartridge. The front end of a nicely shaped aluminum trigger guard is held in place by a vertical screw inside the stock. It is accessible when the barreled action is removed. The opposite end of the guard is secured by the rear action bolt.

The action rests atop aluminum pillars located in the stock beneath its receiver tang and ring. Measuring 1.140 inches in diameter and 7.875 inches long, the receiver appears to be the same as on other variations of the Model 84M rifle.

A bolt release tab located on the left side is easy to operate. The spring-loaded ejector in the floor of the receiver bridge was obviously borrowed from the Winchester Model 70 design. I consider it an improvement over the Mauser-style ejector, which requires a passage split in the left locking lug.

The receiver is drilled and tapped with 8×40 holes for attaching an included Talley two-piece aluminum scope mount.

The guys at Kimber subjected the bolt to some really serious whittling. Spiraled fluting on its body left a smidgen of weight on the shop floor, as did three lightening cuts in the side of its Mauser-style extractor.

I had seen bolt handles lightened in the past, and I own a few of them, but their modifications are mild compared to this one. The shank of the handle, which was quite small in diameter to begin with, has three lightening flutes extending all the way into a hollowed knob.

The bolt weight is 8.25 ounces. I’m not sure how that compares to a standard Model 84M bolt, but I can tell you that a Remington 700 short action bolt weighs a quarter-pound more.

I have seen lightened bolts with a butchered look, but on the Mountain Ascent it is not only tastefully done, it makes an extremely attractive rifle even more appealing. Equally important, strength and durability are in no way compromised.

The bolt has two ports located just behind its locking lugs. In the event of a ruptured primer or blown case, one port will channel propellant gas into the bottom of the receiver where some of it will escape through a port in the right-hand side of the receiver ring, with any remaining gas making its way into the magazine box. The other port would divert gas into the receiver raceway of the left-hand locking lug. Bolt throw is 4 inches.

Extremely skinny barrels sometimes look odd, but the one on the Mountain Ascent is scaled perfectly in size for the rifle. Beginning at the receiver, its chamber reinforce section is 1.765 inches long and 1.050 inches in diameter. From there it tapers gracefully to 0.565 inch at the muzzle.

Overall barrel length, including a 28-port muzzle brake, is 23.38 inches. The brake is easily removed and replaced by an included thread protector; doing so reduces length to slightly less than 22 inches.

The six-groove rifling has a twist rate of 1:12 inches. Three rather deep lightening flutes run about half the length of the barrel. A washer-style recoil lug is sandwiched between a shoulder on the shank of the barrel and the face of the receiver. Stainless steel is rust resistant but not rust proof, so as an additional touch of Kimber class, the barreled action is further protected from foul weather and hard knocks by a durable KimPro II finish.

The trigger is fully adjustable, but who would want to mess with it since it leaves the factory at 2.5 pounds? The total absence of either creep or overtravel along with a pull variation of only 1 ounce makes it one of the very best triggers available.

I remember when 8 pounds was considered extremely light for a rifle wearing a scope, and back then such luxury was available only to those who could afford a very expensive custom rifle. While that’s still plenty light for most of the hunting most of us do, it is a bit hefty today as a pure mountain rifle goes. Wearing a Weaver 3-10X 40mm Grand Slam scope in the Talley two-piece mount, the Kimber Mountain Ascent I shot weighed precisely 5 pounds, 12 ounces on my postal scale. Add another half-pound for four cartridges and a lightweight sling and its hunt-ready weight is still inside 6.5 pounds. There was a time when any serious sheep hunter would have hocked the family farm for such a rifle.

Outstanding Accuracy
My standard protocol for accuracy-testing a big-game rifle with an extremely light barrel has long been three-shot groups fired rather quickly with the barrel allowed to completely cool down between groups. Done right, it can use up the better part of a day at the range. But I’ve been down that road many times before, and as I usually do, I took along a couple of other rifles that needed to be shot for upcoming hunts. Rotating them along with the Mountain Ascent at the bench helped, but I still had to occasionally sit and twiddle my thumbs while barrels cooled down.

If the rifle has a magazine, I also make it a point to run all test loads through it. While doing so with the Kimber, I was impressed by how smoothly it fed them. It was due not only to proper cartridge feed angles from both sides of its staggered magazine, but the extremely slick surface of the polymer follower as well.

Working with many rifles of various weights through the years has often illustrated to me that accuracy differences between various loads is usually far greater with extremely light rifles than with those at the opposite end of the weight range. Try several different loads in a 12-pound rifle capable of winning registered benchrest matches, and while accuracy will vary, all will still likely average less than quarter minute of angle. Try several loads in a 6-pound rifle, and accuracy spread among them can often be measured in inches.

The Mountain Ascent performed exactly as I had expected. Nosler Trophy Grade ammunition loaded with the 165-grain Partition averaged 1.48 inches, which from a practical point of view is not bad for a flyweight rifle with a pencil-thin barrel. But groups fired with that same ammo loaded with AccuBond and Ballistic Tip bullets of the same weight were twice as large. It was the same story for Barnes VOR-TX, with the 150-grain Tipped TSXBT delivering groups considerably smaller than the same bullet weighing only 18 grains more. With an average of 1.37 inches, Federal Premium High Energy with the 165-grain Trophy Bonded Tip bullet was tops in accuracy among factory loads. From the 22-inch barrel it was also faster than standard-velocity 165-grain loadings of the .30-06 Springfield.

The handloads I used had proven to be accurate in other rifles of the same caliber, which doesn’t always mean a lot since it is rare to see two rifles deliver their best accuracy with the exact same load. But try enough good loads in a good rifle and something might just work. Such proved to be the case with the Swift 165-grain A-Frame pushed along by 46.5 grains of Reloder 15. In addition to being the preferred load of my Shilen-barreled Remington Model Seven, it proved to be the number one choice of the Mountain Ascent as well and averaged 1.11 inches. Anyone who considers that less than outstanding from a 5-pound rifle has not shot many 5-pound rifles.

I found the little rifle surprisingly comfortable to shoot, even with the Swift 200-grain moose bullet. It is not a rifle I would want to blast away with all day long in a prairie dog town, but I shot about 120 rounds from the bench during a single session with nothing but a thin Bob Allen strap-on shoulder pad between it and me. After concluding my accuracy tests, I fired another 20 rounds at 300 yards from the prone position without the pad, and every bullet landed close enough to the center of the target.

In addition to being quite effective at reducing recoil, the muzzle brake did not seem to be as loud as some I have shot. I don’t shoot many rifles with brakes, but when doing so at the gun club, I’ve noticed that other shooters usually make it a point to leave several empty benches between them and me. On the day I conducted the shooting session, the range was busy, and I had shooters at the benches on both sides of mine. Not a single one commented on the muzzle blast from my rifle. In fact, the .264 Winchester Magnum with no brake being shot by the guy several benches down from me seemed much louder.

As has often happened through the years, the guys at Kimber have once again done themselves proud. A serious mountain hunter who has been up there and back a few times will be able to leave the Mountain Ascent on the gunshop shelf only as long as it takes for him to reach for his checkbook. I am usually quite good at finding nits to pick, but I have yet to uncover a single detail begging to be improved or changed.

The camo finish may seem unusual to some, but as I discovered, it is unbelievably effective. While shooting photos of the rifle, I leaned it against a bush and momentarily turned my attention to the camera. When I turned back around, the rifle was either still there and I could not see it or it had magically vanished into thin air. It should eventually turn up, and when it does, I solemnly promise to return it to Kimber.

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  • Tom C

    I understand the concept of a very light rifle, but for the ammount of Money spent for this rifle for the size of the groups, when you can buy rifles out there at 1/3 the cost with the same or better grouping and weighing a little more????? Dont get me wrong I would love to own a Kimber Rifle, but at this point I would rather own 3 nice rifles over this one.

  • dale

    The Kimber84M Mountain Ascent seems to be not so flawless as the article states. The Savage "Light Weight Hunter" in the same caliber weighs only 11 ounces more and costs $1115 less. More than twice the price to achieve so small a weight saving is one BIg flaw. Just taking a half-dosen fewew .308 rounds reaches the same goal

  • idahoguy101

    The Mountain Ascent weigh 9 ounces less than the Kimber Montana. You'll pay $600 over the MSRP of the Montana to save that 9 ounces of weight! Is 9 ounces worth an extra $600?

  • Dano

    The Kimber sounds nice! I use a Tikka T3 in 30.06, set up just like the Kimber up above. Found it to be the lightest and most accurate! Not only that it does not tear your arm off at the range. At approximately $500 plus scope. Not bad! Use to have a Remington 700 BDL. Tikka T3 is all I need from now on.

  • Tim

    I've always wanted a Kimber rifle, and this one looks like a beauty. I use a Remington 700 SPS Tactical in .308 for whitetail, but I strictly stand hunt so the extra weight doesn't bother me. However, I would not want to lug it around all day for mountain hunting!

  • Jack

    Well written article, I enjoyed reading about this rifle. Sounds like a very nice accurate lightweight rifle.

  • Mark

    Mountain hunting is NOT for the faint of hear. If you are fit and otherwise healthy there is no reason to spend so much on a rifle that JUST weights less and but does not deliver much better accuracy than other better priced guns ; at a slightly higher bulk weight. I concur with dale above. 1 lbs, more or less, will not make much difference on my hunt. $1K extra on the price of the rifle does.

  • roy

    for the price it should shoot 1/2 all day at a 100 yards

  • Larry

    Obviously the guys commenting on here are NOT in the market niche for this rifle. YES it is worth the extra money to shave every ounce off, and we are talking hunting accuracy not sitting your butt on the bench shooting. I swear comments from guys who have never backpack hunted especially as you get older. I am 58 years old, and backpack in 3 days at a time elk hunting where I am certainly willing to pay to carry less weight. If you average out the cost vs weight savings on gear over time vs the cost of hunts, it is obvious this is the choice to make! I just question (in the article) why put a 2.5 – 8 at 11.3 ounces vs Leupold ultralightweight 3 – 9 at 7.9 ounces? Why carry that extra 3.5 ounces?

  • Aero

    15,000-100,000$+ for mountain hunts…..yea, 600$ more then the Montana seems like a pretty stiff cost. People complaining about how this is so expensive and innaccurate for a deer rifle, is like comparing the fuel costs on an F-250 vs a Porsche GT3. Different markets, different customers boys.

  • Mystro

    Weight between the Mountain Ascent and Montana needs to calculated with the same caliber. The Montana in 308 weighs 5lbs 2OZ. The Mountain Ascent in 308 weighs 4lbs 13OZ. That’s only 5 ounces different between guns. Then lets consider if you even want a muzzle break??? I don’t so the value of the Montana becomes obviouse. I’ll take a Montana 308 any time and I did. My Montana 308 with the very best Leupold VX6 3×18 Firedot and Talley mounts comes in at 6LBS. Get a Montana save some money and put it into top shelf optics.

  • Mystro

    Just to add to my previous post,….Having THE lightest fly weight gun is one thing. Having a THE lightest fly weight gun with the best equipment on it is quite another. Performance is every thing.

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