Barnes Vor-Tx .308 150 Gn TTSX – Kimber’s Mountain Ascent eats em up

I was in my favorite gun shop in Montana, Shedhorn Sports in Ennis a few weeks ago checking out the racks of guns. Unlike most places that carry guns anymore, Shedhorn has over 1200 guns in stock, including a huge selection of used modern and collector guns. You never know what may be on the rack there and I try to stop in every now and then to take a look. One of my shooting gurus, Tony, works behind the gun counter and when it comes to anything to do with firearms or shooting, Tony can fill you in from both the practical and technical sides of the discussion. I had ordered my .308 Kimber Mountain Ascent from Shedhorn and Tony asked me how it was shooting. He had been curious about the little gun’s accuracy potential from the moment we opened the box. “She’s shooting ok”,  I told him, “but I’m not satisfied with it yet”. Tony walked over to the ammo shelves and came back with a box of Barnes Vor-Tx TTSX in 150 grain. I was a little less than excited because the advertised muzzle velocity with the 150s was 2820 FPS and Hornady and Federal had 165 grain loads advertised at 2860 and 2880 FPS. I had been working with the Hornady Superformance loads and still had a full box left, so initially I passed. That night I did a little research on the Barnes ammo on the web and was impressed with the penetration tests and weight retention of the solid coppers. In all cases, the Barnes 150 grain TTSX penetrated substantially deeper than any other bullets, including Nosler Partitions.  I figured they might be perfect for anchoring  tough mountain goats, so I called Tony back and asked him to tuck the two remaining boxes away.

You can read about the other shooting sessions with the Mountain Ascent and the Nosler, Hornady and Barnes ammo in my other articles under the “Shooting” category. To summarize, the Barnes loads are tack drivers. Consistent and unflappable. They just kept punching neat 1″ or less 5 shot groups.  I was happy with the accuracy but had not verified the velocity.

Tonight I ran three rounds through my chronograph. Barnes  advertises the muzzle velocity (MV) of the loads at 2820 FPS with a 24″ barrel. So I was surprised  when the loads came in at 2847, 2827 and 2836, an average of 2836 FPS with the Kimber’s 22″ barrel. That’s an Extreme Spread (ES) of only 20 FPS, less than 1% dispersion. Any ES of less than 30 FPS is considered excellent.

It was 69 degrees when I was shooting and I wouldn’t be surprised to see the FPS drop a bit at lower temperatures. I may try shooting three rounds out of the fridge to see how the MV changes before sending Leupold my load data for the custom CDS dial.

UPDATE : I put three shells in the freezer and cooled them to what I estimated was 10-20 degrees.  As expected the velocity dropped, with the three rounds at 2804, 2777, and 2796, an average of 2792 FPS. ES was 27 FPS, still very acceptable, but the overall average dropped 44 FPS due to the lower temp shells. So I checked the ballistics calculator and the difference in drop at 400 yards between the two velocities is less than 1″; 21.75″ at 2836 FPS and 22.53 ” at  2792.  Close enough. I am going to have the scope dialed in for 2805 FPS .

Anyway, I am getting close to wrapping up the pre-season work on the Kimber. Its shooting well and its time to get serious about practicing with the bow. I re-fletched all of my arrows that were missing vanes last week and am ready to start popping the Block.  Check out the last 3 shot group from the Kimber.. 3/4″ center to center , in the pic below.