The Kel-Tec P17 barrel was measured at 3.814 inches.

Published Velocities for .22 cartridges are easily available, and are usually measured in rifle-length test barrels. Lapau reportedly uses a 660mm (26 inch) test barrel for .22 rimfire rifle ammunition.  RWS uses a 650mm (25 inch) test barrel for rimfire rifle ammunition.  US manufacturers are said to use 24-inch test barrels. It makes sense manufacturers would use the longest commonly available barrel to test their ammunition.  Velocities of .22 ammunition in the US is seldom given for pistol barrels.

In a previous article, information was published about the velocities of three pistols for five subsonic and suppressor-ready loads.  KevinC, in a comment, asked for a test of common rounds in the advertised 1200 fps range. This correspondent had a number of them handy, as well as some older (1970) Remington Standard Velocity ammunition, recently tested for a different article.

One difference in this article is the reported length of the barrel on the Kel-Tec P17. Earlier, it was reported as 3.93 inches. References to the 3.93-inch length are still found on the Internet. References to the barrel length as 3.8 inches were found as well. The 3.8″ barrel length is now on the Kel-Tec website. Measurement beats speculation. The Kel-Tec P-17 barrel measured 3.814.  Measuring a pistol barrel to the hundredth of an inch seems overkill. 3.8 inches will be used going forward. The pistols were fired with a suppressor.

The results are shown in the chart.

There are sufficient differences in barrels to affect velocities from firearm to firearm. However, the results, in the aggregate, are reasonable.

The 5.5-inch CP33 produced, on average, velocities 45 fps greater than the 3.8-inch barrel of the P17. The Taurus TX22, with a 4.1-inch barrel, was in between, with average velocities 16 fps more than the P17 and 29 fps less than the CP33.  The velocity difference between the 3.8-inch and 5.5-inch barrels is 20 fps more than in the subsonic cartridges measured earlier. As expected, the higher velocity cartridges are not as efficient in shorter pistol barrels.

The velocity measurements were taken with a  Caldwell Chronograph G2. The pistol velocities are the average of five shots, except the 1970 Remington from the P17. The five-shot run was duplicated as part of another test, so the entire 10 shots were used for the average. The temperature was between 65 and 75 degrees Fahrenheit.

All the cartridges measured averaged subsonic velocities from the pistol barrels. One round of Remington Golden Bullet ventured into supersonic range from the CP33.  The four cartridges advertised as supersonic were supersonic from the 18 inch rifle barrel.  Five of 25 of the 1970 Remington Standard Velocity cartridges had a noticeable supersonic crack, fired from an 18-inch barrel.

Most of the noise produced by cartridges fired through a suppressor can be categorized as muzzle blast or supersonic crack. In the author’s subjective experience, the higher velocity cartridges increase the muzzle blast, even when the bullets are subsonic. The more efficient the suppressor, the less this is noticeable.

One advantage of subsonic velocities from the pistols is the “High Velocity” cartridges are often less expensive than dedicated subsonic or suppressor-ready cartridges.

.22 rimfire pistols are very loud compared to rifles. It takes a more efficient or larger suppressor to reduce the noise to ear-safe levels. Having reliably subsonic ammunition makes this much easier.

About Dean Weingarten:

Dean Weingarten has been a peace officer, a military officer, was on the University of Wisconsin Pistol Team for four years, and was first certified to teach firearms safety in 1973. He taught the Arizona concealed carry course for fifteen years until the goal of Constitutional Carry was attained. He has degrees in meteorology and mining engineering, and retired from the Department of Defense after a 30 year career in Army Research, Development, Testing, and Evaluation.

Dean Weingarten

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