9 mm Revolver Bores

by
posted on June 11, 2014
** When you buy products through the links on our site, we may earn a commission that supports NRA's mission to protect, preserve and defend the Second Amendment. **
201089141944-sw_carry_m-1.jpg

A few years ago, I was deeply involved in persuading Smith & Wesson to build a particular model for the concealed-carry handgunners of this country. As many readers are aware, I am a big fan of the internal-hammer Centennial revolvers. I have been carrying them daily since the early ’70s and consider them to be the ideal concealed-carry handgun. Naturally, I was delighted when the company developed a light .357 Mag. Centennial, and I carry one of these every day. But, in a handgun world awash in 9 mm semi-autos, I felt-and still feel-that the company needed to offer a light 9 mm.

Thus began a series of experiments to prove that this might be a good idea. The firm did offer a stainless steel 9 mm Centennial at this point in time, but it was too heavy to expect habitual carry by all but the most dedicated. I ran a series of chronograph tests comparing velocities of the same basic gun in 9 mm Luger and .38 Spl. If you kept bullet weights the same-124 to 125 grs. and 147 to 150 grs. in both cartridges, the results were surprising. The 9 mm gun turned in faster speeds than the .38 Spl. Since the company used the same basic platform for both calibers, the shorter 9 mm round had a lot of freebore in the cylinder. I assumed that the reason for the velocity disparity was the so-called “jump” in front of the cylinder.

It may have been a contributory factor, but I am now convinced that there is another reason. I don’t believe the barrels on those early J-frame 9 mms were really 9 mms. I think they were .38 barrels marked 9 mm. The smaller 9 mm bullet was a looser fit in the larger bore and the velocity was therefore higher. And I also believe that this makes little difference in a short-range defensive handgun. A light 9 mm Centennial is still a good idea.

Latest

Low
Low

U.S. Military Unveils "Drone Killer" Rifle Cartridges

The U.S. military's new Drone Killer Cartridge is designed as a cost-effective family of ammunition designed to increase a warfighter's probability of a hit against drone threats.

I Have This Old Gun: Röhm RG 14

RG Industries was established in Miami, Fla., to manufacture—using many German-made parts—the smallest Röhm-pattern handguns for domestic sale, including the RG 14 revolver chambered in .22 LR.

Review: Primary Weapons System UXR

What if you wanted to have more than one caliber in a single rifle? The Primary Weapons System UXR rifle is the answer, and it takes caliber-interchangeability to the next level.

Holosun Rolls Out New 407, 507 Handgun Optics

New for 2026, Holosun is releasing new versions of two of its most popular handgun optics with the 407 Comp, 407C-X3, 507C-X3 and 507-Promax.

The Armed Citizen® March 2, 2026

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

Nation's Oldest Gun Club Turns 150

The oldest continuously operating rifle club in the United States, the Newport Rifle Club (NRC) near Middletown, R.I., is celebrating its 150th anniversary in 2026.

Interests



Get the best of American Rifleman delivered to your inbox.