9.8 mm or 9.65 mm?

by
posted on January 22, 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. **
wiley-clapp.jpg

The first decade of the 20th century saw a lot of developmental effort in the handgun field. It’s well known that legendary designer John Browning was involved in both American and European firearms design. In 1910, he had all but completed-with Colt and Army Ordnance-the development of the Government Model .45 pistol. Mr. Browning was also working with FN, the national arms plant of Belgium, and had used essentially the same design as the Colt. There were several different Colt pistols that had an FN counterpart. This was done with the approval of all concerned, because the two companies agreed not to sell arms in the others territories. They had literally divvied up the world and everything was working fine.

But they had omitted a few countries, which were open to competition. Romania, down in the Balkans, was such a place. Colt got wind of a Romanian interest in some kind of medium-bore auto. They developed and produced a scaled-down version of the soon-to-be famous 1911 pistol.  In so doing, they created a collector’s item, the 9.8 mm Colt. Only a few were made, because Colt salesmen were unable to sell the Romanian buyers on the gun.

Aware that this was going on, FN came up with a version of the same pistol. Once again, they were unable to sell anyone on the idea and the guns never went beyond the production prototype stage. They used a cartridge called the 9.65 mm Browning. All of this was well recorded in several respected sources. I once saw one of the Colt pistols at an NRA Convention, but was not allowed to handle it. I have never seen the FN gun or the ammo for it. The whole concept is very interesting to me, but the ammunition is even more so. If Colt and FN made essentially the same gun, why did they use two different cartridges?

It looks like they didn’t. The 9.8 mm Colt and 9.65 mm Browning are (nominally) .15 mm different in size. In English measurement, that is about .0059-fifty-nine ten thousandths-of an inch. That really is not much. As a matter of fact, it’s just about the difference between bore diameter and groove diameter. I would bet serious money that this was the difference between the 9.8 mm Colt and the 9.65 Browning. One company named its round on bore diameter, the other on groove. There is no real difference.

Latest

Winchester Super Match 01
Winchester Super Match 01

Competition Ready: Winchester's New Super Match Ammunition

Winchester Ammunition has answered the call of competitive shooters with its new Super Match lineup, comprised of cartridges tailored to perform in a variety of events.

A Brief Beginner's Guide to Buying a Defensive Handgun

After running a gun shop and an indoor range for more than a few years, one American Rifleman contributor has a few tips for those looking to buy their first handgun.

Gun of the Week: Wilson Combat Bulwark

Wilson Combat has long been known for its custom work on 1911-style designs, but the company also develops its own firearms, and one of its latest in-house creations is the new Bulwark.

The Armed Citizen® Sept. 4, 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.

NFA Wait Times Continue to Drop

In early 2021, it took the ATF about 280 days to process a Form 4 NFA transfer. In August 2026, using the recently implemented eForms system, that wait time had dropped to only nine days.

Pelican Air Carry-on Case Review

An industry staple just made air travel more convenient.

Interests



Get the best of American Rifleman delivered to your inbox.