The idea of having a sidearm and longarm in the same caliber goes back centuries. During muzzleloading days, simply having a pistol in your belt with the same bore size as your rifle greatly simplified your ammunition supply, since you only needed to carry one size bullet. Just remember to use less black powder in your pistol. While most people through most of history wanted a larger diameter bullet for their handguns - which would increase effectiveness at the lower velocities produced by the shorter barrels - some military units were, indeed, equipped with rifles and handguns using the same bullet. So were some exploration expeditions. (Did you know that Lewis and Clark decided not to carry black powder, and instead used pneumatic rifles? But I digress...)
Come the age of cartridges and things were a bit different. These had factory-measured powder charges already inside, so a rifle and revolver combo both chambered for the same cartridge left you with either a revolver shooting a rifle load or a rifle shooting a handgun load. Most such combos used unusually potent (for the time and even today) revolver cartridges, such as .44-40 or .45 Colt. Besides ammunition commonality, the longer barrel of the rifle extracted more useful energy from the powder charge, resulting in a higher muzzle velocity for the same bullet weight. Just as long as the barrel isn't too long. For most such combinations the rifle was designed as a carbine; that is, a short, light, handy rifle of low or intermediate power. Lever action rifles were especially popular for such combinations. Full-sized rifles, with their longer barrels and heavier weights simply were not needed or appropriate for this application.
Even today there are advantages to such an arrangement. While not quite the same situation, the US military uses both the M16 assault rifle and the M4 carbine, the latter being a compact firearm even shorter than the carbine-size M16. It has basically replaced the submachine gun for troops fighting in tight quarters or doing house clearing. The shorter barrel of the M4 (14.5 inches) does not get as much performance from the 5.56 NATO cartridge as the M16 (with a standard barrel length of 20 inches), though it still produces significantly greater muzzle energy than typical submachine guns. A huge amount of work has been done to create loadings for the 5.56 cartridge which work adequately in both weapons. Even with the relatively small difference in barrel length between the two weapons this has not been easy. Note that the barrel of the M4 is so short it would be considered a short-barreled (or "sawed off") rifle by the BATFE and not legal in the US, even in a semi-auto civilian version. Though a semi-auto version with a longer barrel (16" is the legal minimum length for rifles by federal law) would be. This sort of thing has been done before.
The M4 is not the first time a shorter firearm chambering the 5.56 round has been tried. During the Vietnam war there was a semi-experimental, cut-down M16 designated the MX177. Unfortunately, part of the advantage of the shorter barrel was lost due to needing a much longer flash hider than the standard rifle. (More on why this was needed below.) Other short-barreled variants were tried and rejected before the M4.
Many companies still make both handguns and rifles - usually revolving handguns and lever-action carbines - which feed the same cartridge. These are often manufactured in matched sets. More often the companies are just making the same handguns and rifles in multiple calibers, with some overlap, without them being specifically matched. Given modern bullet designs and powder formulations these are actually much more successful than such combinations were in the black powder days. As was true back then, these usually involve the more powerful handgun cartridges, though many such pairings are also made in .22 rimfire.
I have long had a Ruger single-action revolver - a New Model Blackhawk, which strongly resembles the old Colt Single-Action Army but which is made with modern alloys and safety features - and a Marlin lever-action carbine chambered in .357 Magnum. While the primary goal is to be able to have them shoot the same loads, I also worked up a handload for the carbine to get the most out of that longer barrel. It uses a heavy bullet for the caliber in front of a near-maximum charge of slow-burning pistol powder. This can be fired in my Ruger Blackhawk (they're extraordinarily strong) but won't come anywhere near the potency the same load has from the Marlin. To illustrate why, I give an extreme example from personal experience.
I took some of these dedicated carbine-loaded cartridges - with the rifle - to a party on a farm which included some informal shooting. One of the other participants had brought a full-frame sized but short-barreled .357 revolver. Even though I cautioned folks that these were my handloads and not factory ammunition, there was soon a line to shoot those cartridges in that gun as the sun went down. Just to see the two-foot wide ball of fire come out the muzzle with each shot in the gathering twilight. That sizable flame occurring because the slow-burning pistol powder was not being completely consumed before the bullet left the muzzle of the short-barreled revolver.
Why do I have such a rifle/revolver combination? Pure nostalgia. This gives me a handgun and carbine in the same (though not historically valid until 1935) loading, as some of my predecessors had. I also have a traditional-style cartridge belt and holster for .45 Colt and the .327 Federal (a relatively new cartridge) to go with combinations of handguns and rifles for both cartridges. Though these rig are more for collector value than practical use I do sometimes bring one of the combos to the range. That always elicits favorable comments. The leather work on these is remarkable.
Overall, the revolver/lever-action carbine combination in .357 Magnum works quite well. Magnum cartridges typically have more powder than can be completely burned in most handgun barrel lengths, to get the high velocities such rounds are known for. The longer barrel of the carbine makes good use of this extra powder. (Shooting a pistol cartridge in a very long rifle barrel can actually result in a reduced muzzle velocity, when compared to a carbine-length barrel. The pistol charge of powder just isn't enough to overcome the added drag of the longer bore. This is particularly true with the very popular .22 Long Rifle. Even though - as the name implies - it was designed for use in rifles.)
With similar bullet weights, a .357 Magnum cartridge at full factory pressure shot from a carbine has ballistics very close to those of the .30 Carbine cartridge/rifle combination. While that is not by any definition a full-powered classic military battle rifle cartridge - looking puny even beside such medium-powered modern military cartridges as the 5.56 NATO - it is still potentially lethal out to 300 yards, as demonstrated in several wars. Note that it achieved these results with a full metal jacket bullet. With a jacketed hollowpoint or jacketed softpoint of modern design both the .357 and the .30 Carbine do far better. Though not for much further than that, due to both cartridges being designed for bullets which are not streamlined for long range use.
A more modern cartridge well suited for the combination of handgun and rifle is the .327 Federal, mentioned above. This cartridge was developed in 2007 for hunting and target shooting with revolvers. It is an ultra-high pressure cartridge meant strictly for modern, high strength handguns. Several revolvers have been chambered for it, but until 2018 no rifles came from the manufacturer chambered for it (though some existing rifles were modified by gunsmiths). That has changed with the Henry Big Boy lever-action rifle in .327 Federal, which just came on the market as this is written.
Very early in its history, fans of the .327 noted that it would greatly benefit from a longer barrel than you can reasonably get with a handgun. There was precedent for making such a firearm, since the ballistics of the .327 are close to those of the .32-20 Winchester cartridge, which has been around since 1882. That was designed from the start as a light rifle cartridge for small to medium game; however, there were also handguns made for it. As there were for the .30 Carbine. Both rounds - being intended for rifles - made poor handgun ammunition. The slower-burning rifle powder meant that - as with my .357 Magnum carbine load - much of the powder burned past the muzzle in a handgun. This produced a very unpleasant flash and bang. However, several designs of handguns for both the .32-20 and .30 Carbine were made with thousands sold.
The .327 Federal started as a revolver cartridge, a lengthened and strengthened version of the .32 H&R Magnum, itself a round only developed in 1982. The main complaint about the .32 H&R was that it wasn't powerful enough. With the .327 that flaw is corrected. The new cartridge is roughly equivalent ballistically to the .38 Special +P; a higher-pressure loading of the classic .38 Special which is intended only for strong, modern firearms. Also, as with the .357 Magnum, while the .327 is meant for handgun use it benefits from a carbine-length barrel.
The Henry Big Boy is meant for cartridges of up to .44 Magnum, another modern handgun cartridge popular for handgun/carbine combos. All variations of the rifle are very sturdy... and very heavy. Actually too heavy for the .327. However, at the time this is written it is the only factory rifle chambering that cartridge. That may change if it proves popular enough.
There has been talk for decades about finding a way to make a cartridge of variable "output" for the military to use in both assault rifles and handguns. There are theoretical ways to produce one cartridge which will get full use of a carbine-length barrel but not produce the flash and bang which normally results from shooting a rifle cartridge in a handgun. So far there has been little practical result.
If
someone does manage this very difficult task it would likely be
eagerly adopted by some branches of the US armed forces. At least,
once the "I only trust stuff that's been used for decades"
mindset is overcome. If that happens, it will greatly simplify
ammunition supply for units so equipped. This document is Copyright 2019 Rodford Edmiston Smith. Anyone wishing to repost it must have permission from the author, who can be reached at: stickmaker@usa.net