Having hunted the eastern woodchuck, in the low-lying dairy farmlands of Connecticut (generally, within 100 ft - 200 ft of sea level), as well as the high-country marmot ("timberline grizzlies"), high above Colorado's timberline (timberline at that latitude, approx. 11,500 ft - 12,000 ft), I can attest to the magnum-like exterior ballistics one experiences, in the latter environment --- with no change in the loading! My favorite high-country varmint rig, back in the 1970's, was a Bullpup'd Remington 40-XB chambered for the 6mm Remington cartridge, with the 80-grain Power-Lokt Hollow Point bullet (BC - 0.255) http://i57.tinypic.com/20zutqu.jpg .
Back to the future. Choosing a high-country varmint rig, today, I'd pick a compact 6.5mm Grendel-chambered Bullpup, with a short 16-inch barrel. And, I'd use the 123-grain Lapua Scenar (BC - 0.527), or the 130-grain Sirocco II (BC - 0.571) loadings.
I recently ran the numbers through the Hornady Ballistics Calculator:
Cartridge . . Elevation . Muzzle V/E . . . . . . . 500 yards V/E . . . . 1000 yards V/E . . . Drift (500/1000)*
6mm Rem., 12,000 ft.: 3480 fps/2151 ft-lb . 2264 fps/910 ft-lb . 1363 fps/330 ft-lb . . . . . . 18.5"/93.9"
(80 PwrLkt) Sea Level: . . . . . . . . . . . . . . . . . . 1698 fps/512 ft-lb . . 915 fps/149 ft-lb . . . . . . 33.3"/184.4"
6.5 Grendel, 12,000 ft.: 2523 fps/1738 ft-lb . 2010 fps/1104 ft-lb . 1569 fps/673 ft-lb . . . . . 12.7"/56.9"
(123 Scenar)Sea Level: . . . . . . . . . . . . . . . . . . . 1745 fps/831 ft-lb . . 1184 fps/383 ft-lb . . . . 21.4"/102.5"
6.5 Grendel, 12,000 ft.: 2425 fps/1697 ft-lb . 1961 fps/1109 ft-lb . 1558 fps/701 ft-lb . . . . . 12.3"/54.7"
(130 Sirocco)Sea Level: . . . . . . . . . . . . . . . . . . 1718 fps/852 ft-lb . . 1200 fps/416 ft-lb . . . . 20.7"/97.3"
The high efficiency of the 6.5mm Grendel cartridge makes it a viable choice.
* Wind Speed, 10 mph; Wind Angle, 90 degrees
Back to the future. Choosing a high-country varmint rig, today, I'd pick a compact 6.5mm Grendel-chambered Bullpup, with a short 16-inch barrel. And, I'd use the 123-grain Lapua Scenar (BC - 0.527), or the 130-grain Sirocco II (BC - 0.571) loadings.
I recently ran the numbers through the Hornady Ballistics Calculator:
Cartridge . . Elevation . Muzzle V/E . . . . . . . 500 yards V/E . . . . 1000 yards V/E . . . Drift (500/1000)*
6mm Rem., 12,000 ft.: 3480 fps/2151 ft-lb . 2264 fps/910 ft-lb . 1363 fps/330 ft-lb . . . . . . 18.5"/93.9"
(80 PwrLkt) Sea Level: . . . . . . . . . . . . . . . . . . 1698 fps/512 ft-lb . . 915 fps/149 ft-lb . . . . . . 33.3"/184.4"
6.5 Grendel, 12,000 ft.: 2523 fps/1738 ft-lb . 2010 fps/1104 ft-lb . 1569 fps/673 ft-lb . . . . . 12.7"/56.9"
(123 Scenar)Sea Level: . . . . . . . . . . . . . . . . . . . 1745 fps/831 ft-lb . . 1184 fps/383 ft-lb . . . . 21.4"/102.5"
6.5 Grendel, 12,000 ft.: 2425 fps/1697 ft-lb . 1961 fps/1109 ft-lb . 1558 fps/701 ft-lb . . . . . 12.3"/54.7"
(130 Sirocco)Sea Level: . . . . . . . . . . . . . . . . . . 1718 fps/852 ft-lb . . 1200 fps/416 ft-lb . . . . 20.7"/97.3"
The high efficiency of the 6.5mm Grendel cartridge makes it a viable choice.
* Wind Speed, 10 mph; Wind Angle, 90 degrees
Comment