January 04, 2011
We American riflemen thirst for velocity...
The fastest animal on earth, the snail!
We American riflemen thirst for velocity. This is not a new phenomenon. Nearly a century ago, Charles Newton broke new velocity thresholds and fueled our imaginations. A generation later, Roy Weatherby was so passionate and so successful as a marketer that, in the late 1950s and early '60s, he took us into a nationwide magnum mania.
After an era of relative calm, in the 1990s a new sultan of speed, John Lazzeroni, burst onto the scene. As did Roy Weatherby, Lazzeroni goaded (or frightened) the majors into a new magnum craze. In just the past decade we have seen a bewildering host of short magnums, ultra magnums, super short magnums, short action ultra magnums, compact magnums and even a small handful of plain old "magnums."
Today, most serious shooters have access to chronographs, so there isn't much blue sky in published figures. Most of the hot new cartridges do exactly what they are purported to do, and many of them do it more effectively from more compact packages.
Our century-old search for enhanced performance has been elusive. In 1915, the .250 Savage effectively crossed the 3,000 fps barrier, and in 1935, the .220 Swift broke 4,000 fps. This velocity is attainable in some varmint cartridges, and occasionally with big cases and light bullets, but there are no big game cartridges that reach 4,000 fps with normal bullet weights.
The best we can do is somewhere in the mid-3,000s, and many of our most popular cartridges fall well short of 3,000 fps.
Now, there's nothing wrong with velocity, especially with tough modern bullets that will hold up at all achievable velocity levels. Velocity flattens trajectory and, perhaps more important for the hunter, increases energy.
Velocity also increases recoil at the same exponential rate that it increases downrange energy, and it increases muzzle blast. It's probably sensible to ask how much speed (with both benefits and baggage) we really need--and, more importantly, to recognize that accuracy and knowledge remain more important.
The thing is, with better optics, better bullets, more precise manufacturing and laser rangefinders it truly is practical to expand our range envelopes, but velocity gains have not kept pace with these developments.
We have the velocity to shoot game without holdover out to perhaps 300 yards, but it is not possible to shoot game at 400 yards without adjusting for trajectory. Once we start holding over, it's simply a matter of degree. Knowledge of trajectory and effect on your sighting system are essential.
Whether it's 200, 300 yards or beyond, once you reach the point where holdover is required, velocity is just a number, so raw bullet speed is considerably overrated. Perhaps the best illustration of this is the 7.62 NATO (.308 Winchester). It misses the 3,000 fps threshold by hundreds of feet per second, but on targets and in combat it remains a solid performer that, in skilled hands, performs well at ranges far beyond sensible hunting distances.
Just yesterday I sat down with a Rock River AR in 7.62 and a Nikon scope, and addressed a steel silhouette at 600 yards. I held halfway between the third and fourth mil dot down and a bit left into the light breeze. The first shot was high on the left side, so I centered the third mil dot and tightened the windage to just off the left side of the silhouette. The rest of the magazine peppered the center of the steel.
Handloaders appreciate that, most of the time, the best accuracy is obtained by backing off from maximum velocity. And yet we still thirst for velocity, and I buy into it just like most of us.
Recently, I committed to take the brand new .300 Blaser Magnum on a sheep hunt in Nepal. Case capacity of this new unbelted cartridge exceeds the .300 Winchester Magnum, so I expected the 180-grain Barnes TTSX load to be about 3,000 fps. The first run of Norma's prototype ammo clocked just 2,850 fps, which is just a fast .30-06 load. I wasn't just disappointed; I was concerned, because I would be taking this load on a high-altitude hunt where long shots were likely.
I needed exact velocity from the chrono to check stadia line values with the Zeiss Rapid-Z reticle. The second step was to check groups, and all of a sudden I felt a whole lot better. The Blaser R8 grouped this load extremely well, consistently under an inch--occasionally under a quarter-inch when I did my part. The accuracy I needed was there, but what about the velocity?
According to the Zeiss Rapid-Z Ballistic Calculator, at an anticipated maximum of 14,000 feet elevation with that bullet (BC .484) at 2,850 fps, a sight-in of 1.3 inches high at 100 yards put me on at 200. At my maximum power of 12X, the No. 4 stadia line was valid at 373 yards; the No. 5 line was valid at 465 yards. I could work with this.
But just suppose I'd gotten instead the 3,000 fps I expected? Keeping the altitude, I plugged in 3,000 fps with the same bullet. Sure, there was a difference. At 3,000 fps a sight-in of 1.07 inches high would be on at 200 yards. The No. 4 line (at 12X) would be valid at 392 yards; the No. 5 line would be valid at 494 yards.
Game animals rarely stand at exactly 400 or 500 yards, so what mattered was to understand the numbers and how my trajectory related to my reticle. Would a difference of .23-inch for a sight-in make any real difference, and could a hunting rifle be zeroed with such precision? At longer ranges, would stadia line values varying 20 or 30 yards make any difference? Would a couple hundred foot-pounds of energy more or less make any difference?
The obvious answer to all these is "no." What mattered was having the accuracy I needed, the knowledge of how to use the trajectory, and the cool to put it together when it mattered. My Himalayan tahr was taken at 460 yards, dead-on hold with stadia line No. 5. My blue sheep was taken at 495 yards, also a dead-on hold with stadia line No. 5 because of a downhill angle.
I never missed the 150 fps I felt I was lacking. In future I can probably regain that velocity in that cartridge, but if more speed makes the groups open up, I'd just as soon keep the slower load. It was plenty fast enough to get the job done.