Near Zero

by
posted on April 9, 2012
20124992032-nearzeroblog8-9pix-008_m.jpg

As an amateurish but enthusiastic student of Marine Corps history, I remain fascinated with the battle of the Chosen Reservoir. One of the more interesting aspects of this battle was the performance of the various firearms the Marines used 60 years ago. Most of the Browning-designed guns did pretty well, but the M1 Carbine and the Garand rifle did not function with their customary reliability. A lot of this had to do with ammunition, which is what I’m dealing with here. Cold weather can have an impact on the performance of ammunition and there were a number of reports that the point of impact changed on various firearms shot at the Frozen Chosen.

A few years ago, I was doing some in-depth shoots involving the handloading of magnum revolver ammunition. I was living in California at the time and had lost my range, so I was traveling to Wickenburg, Ariz, to shoot with my old partner Stan Waugh who had moved there and was burning his powder at the Wickenburg Sportsman's Club. The range was excellent and the trip was worth it. Most people see Arizona as a very hot place, which can be true. But the winters can be mighty cold and the northern part of the state gets some pretty heavy snow. I doubt that the Arizona desert ever sees temperatures as low as the Chosen Reservoir, but the old thermometer sometimes heads in that direction. On one memorable occasion, we did a shoot that produced some graphic effects of cold weather on ammunition.

We were working up accurate loads for .357 Mag. revolvers, using heavy bullets and slow-burning powders. As was our custom, I was working the guns (mounted in machine rests), as well as keeping the records of chronograph results and changing the targets. Stan was set up at an adjacent bench with a loading press (Ponsness-Warren P200), scale and powder measure. The procedure went like this: I would come up with a load combination based on prior research and call it out to Stan who would assemble it and pass it over to me. I would load the gun, fire a five-shot group, and on the basis of the performance of that load, give Stan the change in powder charge for the next load. Of course, I was chronographing each load as I went along. Everything was proceeding OK, as this was the system we had established years earlier. However, the temperature was 23 to 24 degrees on this chilly winter day.

After several loads were assembled and evaluated, I noticed an unusual pattern. The first shot in any group landed about 1.5 to 2 inches above the point of impact of the other four shots in the group. Also, velocity of that first shot was approximately 25 fps slower than the following four shots. This happened with every load, no matter what it was—first shot 2 inches higher and was 25 fps slower than all other shots with that load. Since the Freedom Arms revolver is probably the most accurate revolver on earth, it was monotonously the same with every load—a high first shot flyer followed by four shots in one hole. What was causing it?

The only constant in the equation was the ambient temperature. The gun was cold for that first shot, because enough time passed while Stan was loading five rounds for the gun to cool off. The cold gun produced a slower velocity. The bullet spent a longer time in the barrel, so recoil moved the gun's muzzle upward slightly farther and the bullet struck a little higher on target. Shooting itself warmed the gun up and subsequent shots were in the barrel for less time, striking lower on the target. In order to get results that were not skewed by the temperature, I asked Stan for six rounds instead of five. Then, I would fire the first one over the top of the target and have the chronograph forget that velocity. Then I would quickly eject that first cartridge, reloading the chamber with the sixth one. In this way, I got the five rounds through a warm gun.

This is useful information. What would happen if a shooter was shooting coyotes on a cold morning on the plains? Say the target was 200 yards away and the gun was cold. At 25 yards, it shoots 2 inches high; at 100, it's 8 inches and it's 16 at 200. Thus, the first round is over the target's back. There won't be a second shot, because mama coyote raises no stupid children and the target is gone.

Latest

Win94lead
Win94lead

The Winchester Model 94: History & Disassembly

Compact, reliable and powerful, Winchester's Model 1894 lever-actions may not have the popularity it once had with Western settlers, prospectors, law enforcement officers, hunters and ranchers, but its legacy remains today and is a fan favorite in Winchester's current product line.

NRA Gun of the Week: Fabarm USA Autumn

On this week’s “Gun of the Week” video preview, American Rifleman examines a first from Fabarm, a side-by-side break-action shotgun called the Autumn.

The Armed Citizen® Sept. 17, 2021

Read today's "The Armed Citizen" entry for real stories of law-abiding citizens, past and present, who used their firearms to save lives.

EOTech Launches Anti-Counterfeit Measures

EOTech has launched a campaign targeting those who create and sell illegal copies of its military sighting systems.

The .405 Winchester: History and Performance

Now largely a forgotten footnote in cartridge development, the .405 Winchester was once the most powerful rimmed cartridge capable of use in a lever-action rifle and was a favorite of Theodore Roosevelt.

Colt Mustang .380 ACP: The Pocket-Size 1911

Based off the classic 1911 design, the small Colt Mustang chambered in .380 ACP is easily concealable and shares the same classic look in its tiny frame.

Interests



Get the best of American Rifleman delivered to your inbox.