The F.I. Combo Pistol/Carbine

Readily converting a handgun into a carbine in mere seconds, in the field, without tools, is an idea that goes back at least to the 17th century, when the snaphaunce was evolving into the flintlock. However, it took the invention of the semiautomatic action for the concept to really catch on.

The earliest descriptive reference I could find to a successful pistol-into-a-carbine that was actually fielded identifies the Springfield Model 1855 pistol with the Maynard tape priming system (though Harper’s Ferry concurrently made a handful with the percussion ignition system). Consisting of nothing more than attaching a separate, temporary buttstock to the pistol, it wasn’t popular, especially among the cavalry, for whom it was intended, so perhaps calling the mating “successful,” is a bit generous. While it is no great engineering matter to attach a buttstock to a handgun, we’re still left with a pistol-length barrel with pistol-length sight radius and no forearm to grasp. That awkward shortcoming is what prompted the saying, “Attaching a buttstock to a good pistol turns it into a bad rifle.”

However, the two-fer-one idea has persisted, most famously in attaching quick-disconnect buttstocks to the Mauser C96 “Broomhandle” and Luger military pistols. Here in the US, the National Firearms Act of 1934 (NFA) regulates short barreled rifles (SBRs), those with barrels less than 16 inches in length, and attaching a buttstock to a handgun is considered making it an SBR. However, there are exceptions to the rule, such as the above-mentioned historical curiosities. 

Today there are a number of inexpensive conversions kits for the Glock pistol that are essentially complex buttstocks that circumvent NFA regulation on a technicality by designing the buttstock as a supposed arm brace and that is nonetheless shown fired with the “arm brace” braced against the shoulder. These have the same shortcoming as their predecessors in utilizing short-pistol barrels. There is at least one

manufacturer I know of today that offers a barrel/stock assembly for the Glock, Model 1911 and Springfield Armory XD/XDM pistols that features a true carbine-length barrel. Another offers a 16-inch barrel and a buttstock attached to a Model 1911 mainspring housing. These finally eliminate the pistol’s short-barrel shortcoming, but the idea is not original; it goes back more than 60 years.

Forgotten now is perhaps the first commercially and practically successful idea in a true pistol-carbine conversion, the FI Combo of the 1960s that mounted the French Unique Model L pistol to an American barrel/stock assembly. This melding of French and American engineering attaches a shoulder stock and lengthens the barrel, and the conversion is indeed achieved within seconds, in the field, without tools. More than that, the conversion produces a full-on carbine from an accurate pistol. Sadly, the FI Combo was legislated out of existence in 1968.

French company Manufacture d’Armes des Pyrenees Francaises manufactured the Unique Model L pistol, but the carbine barrel/stock of the FI Combo was originally a product of the American company Firearms International Corporation (FIC) of Washington, DC (not to be confused with the current Firearms International, Inc. in Texas). France turned out two variants of the FI Combo for the European market called, unsurprisingly, the “Combo” and the “Konvert.”

Offered in 22 Long Rifle, 32 ACP and 380 ACP, Unique Model L pistols are somewhat under appreciated, as they were well-made and earned a reputation for reliability and surprising accuracy in such a small handgun. A May 1962 American Rifleman “Dope Bag” evaluation fired 500 rounds through a 22 Long Rifle Unique Model L pistol without a malfunction, and with five 10-shot groups at 50 feet averaging an eyebrow-raising .47 inch – and this from a barrel only 3.3 inches long.

The 22 Long Rifle FI Combo hit dealer shelves here in 1960, selling for $65 (about $693 in 2025 dollars), but by 1969, it

was no longer offered, having fallen victim to “Saturday night special” fever with the Gun Control Act of 1968 that prohibited further importation of small handguns. But even before that, the FI Combo was immediately questioned as comprising a pistol with a shoulder stock in violation of the National Firearms Act of 1934. Logic prevails only occasionally in government, but it accepted the argument that the FI Combo was, yes, either a 3-inch barreled pistol or an 18-inch barreled carbine, but no, it could not possibly be operated as a 3-inch barreled SBR.

Converting the FI Combo from an evil Saturday night special to an innocuous 22 carbine requires first removing or at least dropping the Unique’s magazine an inch or so out of its locked-in position. Rotate the pistol’s safety lever so that it covers the red dot (on safe), lock the slide back and remove the pistol barrel to the rear. The Unique has an “open slide” like some of the Beretta pistols, as opposed to the “closed” slides of most modern semiautomatics, so barrel removal does not require removing the slide. Ease the now-exposed recoil spring guide rod into the carbine stock’s operating rod tube while tipping the pistol frame upward into the assembly so that the carbine barrel’s tenon properly engages the pistol frame. Pull rearward on the pistol to slide it into place on the barrel tenon and insert the magazine to lock the pistol frame to the barrel/stock assembly. 

I probably made that sound more complicated than it actually is, though I’ll admit it took me a few minutes to figure it out. Thus, assembled into a carbine, now what is the owner to do with the pistol barrel so that it isn’t lost? I received this FI Combo assembled, and the owner didn’t know how to remove the pistol from the barrel/stock assembly. After I accomplished that, I thought, “Too bad the pistol barrel is gone, that certainly lessens its value and historical interest.” Later, while examining the FI Combo, I noticed a faint rattling in the buttstock as I handled it. In an epiphanous moment accompanied by a chorus of jubilant eurekas, I discovered that the pistol barrel is cleverly stored in a recess under the buttplate. If you inherited one of these Combos missing the pistol barrel, turn out those two butt-plate screws and take a look. 

Weighing about 4½ pounds assembled and measuring 34 inches overall, the FI Combo is about three inches shorter than a standard Ruger 10/22. Length of pull (LOP) spans a full 16 inches, though two to three inches more than expected on a long gun, it is surprisingly unnoticeable, at least when not wearing a heavy coat.

Wood appears to be straight-grained American walnut. In an unusual reversal of the typical two-piece stock configuration, the FI Combo features a lower handguard rather than an upper handguard. Two Phillips-head screws on the lower handguard affix it to the stock and barrel via two bosses; removing the handguard provides access to the op rod and spring. The plastic buttplate on this FI Combo is broken at one of the screws, but the maker’s logo is still clear and sharp.

A simple stamped steel affair, two screws attach a notched plate to the rear sight base. An ordinary sliding elevator provides a coarse elevation adjustment for the rear sight. Quite unusual in configuration, the front sight is a bead on a post, mounted off-center atop a short vertical cylinder. It adjusts for windage by loosening a set screw at the front of the ramp and rotating the cylinder in either direction. Because the post is offset from the center, rotating it moves the post left or right from the center. Unfortunately, the protective sight hood is missing from this example. On the positive side, someone mounted an adequate period-ish Bushnell 3X-7X Custom .22 scope to the carbine’s tip-off rail.

Reminiscent of Winchester’s Model 1903, initial cocking and charging of the first round is accomplished via the op rod protruding from the front of the stock below the barrel. Pushing rearward on the op rod retracts the pistol’s slide; releasing the op rod permits the pistol’s recoil spring to carry the slide forward, stripping a round from the magazine and chambering it. Action, of course, is semiautomatic upon firing.

With the safety lever in the “safe” position (red dot covered), pushing the op rod fully rearward locks the action (pistol slide) open, whether or not the magazine is installed. The slide must be locked open, and the magazine must be removed or dropped slightly to remove the pistol from the stock.

At the range, the FI Combo was a bit disappointing in the accuracy department, as a somewhat loose fit of the pistol frame to the carbine barrel tenon allowed the pistol frame to rock a few thousandths up and down, which was likely the cause of vertical stringing. A stiff seven-pound trigger pull weight didn’t help, either. At 50 yards from a rest, groups averaged about two inches vertically, but only about three-quarters of an inch horizontally. Without that vertical stringing, groups would likely have been quite good.

An “exploded view” schematic of the Unique Model L pistol can be found in the Firearms Guide 14th Edition (FirearmsGuide.com). Several parts houses, including Bob’s Gun Shop and Numrich Gun Parts, list parts for the Unique Model L pistol, but an internet search turned up none for the barrel/stock portion of the FI Combo. Nor could I find a schematic for the barrel/stock assembly (though none is really needed, as its assembly is intuitive). Bob’s Gun Shop lists a 22 Long Rifle magazine for $35. A search also failed to show what online auction buyers are currently paying for examples of the FI Combo; however, about 10 years ago they fetched $482 to $901 on online auctions, with four examples averaging $609. 

The current Blue Book of Gun Values ranks the Unique Model L pistol about on-par with Grandma’s ceramic teapot at $90 in 60 percent condition and $300 for a mint example, but adds $500 value as a FI Combo. Interestingly enough, that’s the same value the Blue Book listed 10 years ago, the amount Combos were actually garnering then, and adjusted for inflation, nearly what they sold for in 1960 in 2025 dollars. In the end, when I finished with this FI Combo, it fetched $800 at a gun show. The FI Combo, then, unlike our similarly priced cellphones that become worthless in five years, holds its original value even six decades later.

Not bad for an idea that took 400 years to mature.