March 12th, 2013

CZ Offers New CZ-455 Varmint ‘Tacticool’ Rifle

CZ has introduced a new version of the CZ-455 rimfire rifle featuring a black-finished, laminated wood stock. This new gun, dubbed the Varmint Tacticool by CZ-USA, features a 5-round detachable magazine and adjustable trigger. The new CZ-455 Varmint Tacticool was built as a affordable tactical trainer with the ergonomics and “feel” of a full-size centerfire tactical rig. The Tacticool’s stock looks similar to the Manners Composites stock on CZ’s 455 Varmint Precision Trainer, but the wood-stocked ‘Tacticool’ version is much less expensive. The CZ 455 with Manners stock retails at $899.00 MSRP while the new ‘Tacticool’ model lists for just $522.00 MSRP. The $377.00 you save will buy a lot of ammo (or a scope).

CZ-455 Tacticool Varmint rifle .22LR

We like the looks of the CZ-455 ‘Tacticool’, and the stock has some nice features. The butt-hook stock has ambidextrous palm swells on the grip and a raised comb to provide a comfortable cheek weld for shooting with a scope. The fore-end features a wide, beavertail swell for greater stability on a front sandbag. There are two (2) sling swivel studs so you can attach both a sling and a bipod.

CZ-455 Tacticool Varmint rifle .22LR

Permalink Hunting/Varminting, New Product 1 Comment »
March 12th, 2013

Tuesday Trivia Challenge from Bryan Litz, Ballistics Guru

Here’s a Ballistics Trivia challenge, put together by Bryan Litz of Applied Ballistics LLC. Bryan is Berger Bullets’ Ballistician and the author of Applied Ballistics for Long Range Shooting. Bryan posed the following Ballistics Question about Kinetic Energy and Aerodynamic Drag:

Bryan Litz Ballistics TriviaConsider a .30 caliber 175 grain bullet with a G7 BC of .259 (Berger 175 OTM) fired level at a muzzle velocity of 2650 fps in standard (ICAO) sea level conditions.

As this bullet flies downrange, it loses velocity due to aerodynamic drag. As the velocity of the bullet decays, so does its Kinetic Energy (in ft-lbs). The Kinetic Energy lost by the bullet in a given amount of time can be defined in terms of power.

Another way to think about this is that the aerodynamic drag on the bullet can be expressed in terms of power, calculated from the projectile’s change in Kinetic Energy over flight time.

Question: How much power (expressed in Watts) is applied to the bullet by aerodynamic drag on average over:

A) 500 yards?
B) 1000 yards?
C) 1500 yards?

Guesses are welcome, but this one can be calculated exactly.

Bryan Litz Ballistics Trivia

Permalink Bullets, Brass, Ammo, Tech Tip 4 Comments »
March 12th, 2013

Lapua .260 Rem Brass Proves Very Uniform

If you have a rifle chambered in .260 Remington, you may be wondering if the Lapua .260 Brass is worth the money compared to domestic-made brass. Well, the answer is “yes” if you demand consistent weight and dimensional uniformity (including neckwall thickness).

Mike Harpster of Dead Center Sports took the time to weigh and measure Lapua .260 Rem brass. His test show this brass to be extremely uniform. Weight variance was less than one (1) grain in a 20-case sample. And case neckwall thickness was very consistent.

Report by Mike Harpster: Lapua .260 Rem Brass Test Results (with Comparisons)
I pulled twenty (20) pieces randomly from one Lapua box to do some measurements. I weighed them on my Mettler-Toledo digital lab scale and here are the individual weights of each case. Remarkably, the Lapua brass had less than one grain total weight variance among all 20 cases!

While checking the Lapua brass I remembered I had just received some Winchester brand .308 brass, so I thought it would be interesting to do a comparison between the two brands. I again pulled 20 cases at random from a bag of 50 and repeated the same measurements. The results are shown in the right half of the table below.

Weight Variance Lapua .260 Rem Brass vs. Winchester .308 Brass

LAPUA .260 Rem Brass Winchester .308 Win Brass
Average: 172.20 grains
ES: 0.94 grains
SD: 0.259
Average: 158.49 grains
ES: 2.64 grains
SD: 0.678

Lapua Brass Further Inspection
With sample Lapua .260 Rem cases, I also measured the neck wall thickness in four places with calipers, not the most accurate method but I feel confident that the thickness did not vary more than .001″ over the 20 cases (.0145-.0155). The inside diameter of the neck measured .260 which would give .004 of neck tension out of the box. I visually checked the flash holes and I did not find any flakes of brass or burrs inside, the holes were round and centered.

Winchester Brass Further Inspection
The flash holes on the majority of the Winchester brass were not round or centered and they had large burrs inside. The neck wall thickness was pretty consistent, varying only .0015″ (.0125″ – .014″). As you can see in the photo (right) many of the Winchester cases were badly dented while the Lapua brass showed very few minor dents. The annealing on the necks of the Lapua brass was clearly evident while the Winchester showed no signs of being annealed. [Editor’s note: Winchester tumble-polishes its brass before shipping — so you would not notice annealing coloration if annealing had been done.]

I have never done these measurements on any other brass so I don’t know how they compare, but I am very impressed with the overall quality of the Lapua .260 brass. If they prove to hold up to the repeated firings I get from my Lapua 6BR brass I believe .260 shooters wil be very happy.

Mike Harpster — Dead Center Sports
105 Sunrise Drive
Spring Mills, PA 16875
phone: 814-571-4655
www.deadcentersports.com

Permalink Bullets, Brass, Ammo, New Product 12 Comments »