Shooting Kimber’s Mountain Ascent Rifle in .308 Win

Last weekend I stopped by Shedhorn Sports in Ennis, Montana to see if they had received any H4350 powder. It seems like every sporting goods store in Montana has been stripped of reloading supplies and ammo so I was suprised to find not only the powder, but some Nosler Trophy Grade ammo in .308 loaded in Nosler’s 165 Accubond bullet. I picked up a couple of boxes and on February 12th the weather turned nice enough to put a few rounds through the Mountain Ascent. I did a quick bore site to get the rifle on paper.  Although I was anxious to see how the Kimber shot ( “The only interesting rifle is an accurate one..” Col. Whelen. ) I was actually more interested in the recoil. This was a 4 lb 13 oz gun and I was anticipating it would be substantial. I was pleasantly suprised at not only the mild recoil, but the moderate noise. The rifle  wears a muzzle brake to control recoil but at the expense, I thought, of ear splitting muzzle blast. I guess Kimber has done an excellent job on the stock and the muzzle break design. The recoil was considerably less than my featherweight .270.

I did notice a detectable creep in the trigger, which is a problem that can be easily solved with Kimber’s adjustable trigger.  It breaks light enough, around 3 lbs.

I was shooting off front and rear sandbacgs. Accuracy on my first five shot group was so so. .  around 2.5″.   I decided to try a couple of groups off a bi-pod. Sometimes a different or more consistent pressure point on the foreend can make a difference. Since the barrel was just breaking in,  I gave it a thorough scrubbing with copper solvent, attached the bi-pod, and got ready to shoot another group. First, I set up my chronograph to determine the actual muzzle velocity of the Nosler 165s from my 22″ barrel.

I shot off the bi-pod using just a small sand bag rest under the heel of the stock. Because of the rifles light weight, I held the forend lightly just ahead of the trigger guard to control jump. The first round was through the clean bore and printed a little high and to the right. Not unexpected. The next four printed a nice .82″ group with only .4″ vertical dispersion. With a crosswind  blowing at around 10 MPH, I thought this was excellent performance for such a light rifle.

I’ve recently read a shooter’s review of the Mountain Ascent posted on the net where the rifle printed large groups (3″) with Nosler 165 Accubonds while getting 1.2″ groups with Nosler Partitions.The author noted that ultra-light rifles are generally much more picky about ammo. You need to find the right load. His best groups were with Federal’s Vital Shok P308TT4, .308 High Energy shooting the 165 Trophy Bonded bullet at 2880 FPS. That’s the next one I’ll try, along with Hornady’s 165 Interbonds. While happy with the accuracy of the Nosler load, I was a little disappointed with the velocity out of the 22″ barrel which averaged 2680 FPS.  Nosler advertises the load at 2800 FPS out of a 24″ barrel. While a lot of variables come into play, I had expected a loss of 50-60 FPS due to the shorter barrel which should have left the round at 2740=2750 FPS.  I would prefer the higher velocities of the Federal or Hornady loads if the accuracy is comparable. We will  see how it turns out !