Pellet firing cartridges vs. pellet firing cartridges Part 1 Part 2
By Dennis Adler
The question keeps coming up, is a front loading pellet firing cartridge better than a rear loading shell? I have proposed that the latter produces higher velocity at the muzzle and slightly greater accuracy because the air gets immediately behind the pellet at the moment of discharge, rather than traveling the length of the pellet shell (and thus beginning to expand within the larger circumference of the shell) before it hits the skirt of the pellet to drive it down the barrel. This is, at best, an incrementally small variance, and can only be proven by comparing two different types of pellet loading shells in the same revolver. The question originally came up regarding the recent comparisons between the 7-1/2 inch Colt Peacemaker with rifled barrel vs. the smoothbore pellet-firing Crosman Remington Model 1875. The Remington came in a close second for accuracy behind the Colt. But since both CO2 revolvers use rear-loading pellet firing cartridges, there is no way to use either for testing the front vs. rear loading cartridge theory. I did, however, have one CO2 revolver on hand that can fire either type of cartridge, the ASG Dan Wesson Model 715, which is available with front loading pellet firing cartridges and can also use ASG rear loading cartridges. To test the theory I am using the new rifled barrel 4-inch Dan Wesson Model 715.
The first style Dan Wesson pellet firing cartridge uses a threaded bullet that unscrews, loads the pellet and threads back onto the shell casing. This is a heavy duty brass cartridge with a cast metal hollow point bullet designed to contain the 4.5mm lead pellet. The second type is based on the Colt Peacemaker style pellet firing cartridges (but are not the same), which uses a lighter weight brass case with a rubber grommet at the rear of the shell into which the 4.5mm lead pellet is pressed. Pushed flush to the base of the shell, this seats the pellet directly in line and in front of the revolver’s CO2 valve. When the hammer strikes the valve stem, (what would be the firing pin on a cartridge gun with a floating firing pin) the air is released directly into the pellet’s skirt, rather than first traveling down the length of the cartridge. My theory is that a rear mounted pellet will be traveling faster when it leaves the muzzle than one seated at the front of the cartridge. Granted, that is the way real cartridges are made but the dynamics are different.
What I expected with the two airgun cartridges was a slightly higher velocity from those that load the pellet at the rear. With the 4-inch Dan Wesson Model 715, the variance was significantly more extreme than anticipated. I expected to see from 20 fps to 50 fps difference, I was greatly surprised, and you will be too.
I conducted the test outdoors at a temperature of 68 degrees. The ProChrono chronograph recorded six consecutive shots (waiting 15 seconds between shots) for each of the two cartridges. The first tested were the rear loading ASG pellet cartridges. Velocities clocked 375 fps, 377 fps, 368 fps, 375 fps, 365 fps, and 368 fps. Average velocity was 370 fps out of two tests. I should point out that the Dan Wesson is factory rated at 410 fps. So, it was below maximum rated velocity by 40 fps.
Switching to the ASG pellet firing cartridges that use the front loading bullet, I expected velocities to be relatively close to the rear loading rounds. They were not. Six consecutive shots at 15-second intervals clocked a disappointing 274 fps, 275 fps, 273 fps, 281 fps, 275 fps, and a high of 284 fps; a stunning 96 fps slower than the rear loading pellet cartridges! I ran it again and the differences were still over 90 fps between the rear and front loading pellet cartridges. Both tests results were well below the factory rated velocity for this model. Since the results are limited to this one airgun and its cartridges, it is only a starting point for a comparison but suffice it to say one cartridge type is definitely capable of higher velocities than the other. On another point, the front loading rounds require three steps to load, the rear loading cartridges, one step.
The shooting comparison
A higher velocity does not in and of itself guarantee greater accuracy; to test the two different cartridges the Dan Wesson was fired from a rested position 21 feet from the target, with two targets set side-by-side. It was as close as you can get to consistency from shot to shot outside of using a Ransom rest. At the minimum distance for a rifled barrel pellet pistol, the Dan Wesson placed six consecutive shots (1 inch right and 1 inch low of POA from a fixed position) measuring 0.75 inches with the front loading pellet rounds.
The rear loading cartridges grouped six rounds (0.75 inches right of POA from a fixed position) measuring 0.937 inches. I conducted a second test with a single target firing both pellet rounds offhand using a Weaver stance and two-handed hold. I put six rear loading pellet rounds in the 10 and X at POA measuring 1.24 inches. With the front loading pellet cartridges six rounds grouped into 1.02 inches aimed just below the 10 ring. Clearly accuracy is not influenced by velocity at this range as the front loading pellet shells proved more accurate whether fired from rested or offhand positions.
Is this a definitive answer? I would have to say no, but it clearly supports the theory that there are differences between front and rear loading pellet cartridges, with the same pellets fired from the same gun. My theory about greater velocity with rear loading pellet cartridges seems sound, as for greater accuracy, not so much.
A word about safety
Double Action/ Single Action airguns provide the look, feel and operation of their cartridge-firing counterparts. Most airguns, in general, look like cartrrige guns, this Dan Wesson Model 715 even more so, and it is important to remember that the vast majority of people can’t tell an airgun from a cartridge gun. Never brandish an airgun in public. Always, and I can never stress this enough, always treat an airgun as you would a cartridge gun. The same manual of operation and safety should always apply.