Some pairings look interesting on paper but fall apart in the real world. Whether the recoil doesn’t match the platform or the ammo is nearly impossible to find, some caliber combinations cause more problems than they solve. They might work fine in limited situations or make sense for collectors, but if you’re actually running your gear, you’ll want something more practical.
Here are the combos that don’t hold up when it’s time to get serious.
.410 Bore in a Revolver
The .410 in a revolver sounds versatile, but it’s more of a gimmick than a working solution. The frame has to be oversized to handle those long shells, which makes it awkward to carry and shoot. You end up with a handgun that’s too big for concealment and too short to pattern like a proper shotgun.
You’re not getting real spread or real stopping power. Slugs have poor accuracy, and buckshot often underperforms. If you want a shotgun, carry a shotgun. If you want a pistol, use a caliber made for one.
.22LR and .45 ACP Derringers
There’s no practical benefit to putting .22LR and .45 ACP in the same derringer. You’re either firing a tiny plinker out of an oversized barrel or punishing your hand with a heavy round in a tiny frame. Neither one feels balanced or controlled.
On top of that, the trigger’s usually rough, and sights are barely useful. It’s hard to justify carrying one when a compact 9mm or even a snub .38 does both jobs better without the weird compromises.
5.7x28mm in Oversized Pistols
The 5.7x28mm has potential, but when it’s stuffed into oversized polymer pistols with poor triggers, it becomes more of a range novelty than a practical carry gun. The recoil is light, but the grip is bulky and awkward for most folks.
Ammo’s also expensive and harder to find than standard calibers. It’s marketed as armor-piercing, but civilian loads don’t offer much you can’t already get from 9mm with better support and more compact frames.
.357 SIG in a Subcompact
The .357 SIG was built for barrier penetration in duty-sized guns. When you try to cram it into a subcompact, it loses a lot of what makes it useful. The shorter barrel cuts into its velocity, and the extra pressure doesn’t help follow-up shots.
Recoil’s sharp, muzzle flash is obnoxious, and mag capacity usually takes a hit. It ends up being louder, harder to shoot, and more expensive than a comparable 9mm without much benefit for the average shooter.
.17 HMR in a Revolver
.17 HMR is designed for rifles. In a revolver, you lose velocity, get a ridiculous muzzle blast, and deal with unreliable ignition. Rimfire isn’t known for reliability to begin with, and stuffing it into a revolver doesn’t help.
It’s also a loud little round in a short barrel, which makes it uncomfortable for small-game hunting or pest control. A .22 Magnum makes a whole lot more sense and doesn’t risk the same split case issues either.
10mm in Micro Pistols
10mm is a powerful round, and that’s exactly why it doesn’t belong in micro carry guns. You get brutal recoil, snappy muzzle rise, and real problems getting accurate follow-up shots. It ends up being more of a handful than it’s worth.
On top of that, you lose most of the velocity that makes 10mm worthwhile. You’d be better off with a 9mm or .40 in that same size class if control and real-world use matter to you.
.22LR/.22 Magnum Combo Revolvers
Convertible rimfire revolvers look flexible, but most people shoot .22LR and never bother changing cylinders. The .22 Magnum cylinder sounds good until you realize it’s louder, harder to find, and doesn’t give you much extra power from a short barrel.
Swapping back and forth is inconvenient, and you usually end up picking one and forgetting the other. If you want .22 Magnum, get one built for it. Otherwise, stick with .22LR and save yourself the hassle.
.30 Carbine in Pistols
.30 Carbine needs barrel length to work right. When it’s shoved into a pistol, the round underperforms, the muzzle blast is nasty, and you don’t get the energy it was designed to deliver. It’s loud, awkward, and kind of pointless.
The platform ends up being too bulky for practical carry and doesn’t outshoot modern defensive calibers. It’s more of a range toy than a working gun, and there are better options for every category.
.45-70 in a Revolver
The .45-70 was made for lever rifles, not wheelguns. When you put it in a revolver, you get cartoon-level recoil and a gun that’s borderline unusable without gloves and ear pro. It’s not fun, and it’s not smart.
You also get serious wear on the gun and low shot counts before fatigue sets in. If you want stopping power in a handgun, there are better ways to get there without punishing yourself every time you pull the trigger.
.50 AE in Anything But Desert Eagle
.50 AE exists to be loud, flashy, and expensive. Outside of the Desert Eagle, there aren’t many platforms that can run it properly. And even in the Eagle, reliability can be hit or miss unless you’ve got clean ammo and a solid grip.
You’re also dealing with cost, weight, and size that make it a pain to carry or run for extended sessions. It’s fun once or twice—but it’s not practical for anything serious. There are more useful ways to spend your money.
*This article was developed with AI-powered tools and has been carefully reviewed by our editors.
