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Posted By FFL Dealer Network on 12/18/2018 in Ammunition

The Worst Gun Calibers Ever

The Worst Gun Calibers Ever

or...the Most Useless Cartridges Ever

In the drive to create guns to entice gun buyers to part with their cash, gun makers will introduce calibers and cartridges in hopes of being able to sell more firearms and ammo. 

Some of the cartridges are not completely useless; they can always serve as a bad example. Some are certainly not well-received by the shooting public. Either the round duplicates a tried and true round or it just does not deliver something the gun owning public really wants or needs. Sometimes a cartridge becomes obsolete. Advances in firearms sciences turn it into an interesting historical round. Some are simply the worst calibers imaginable. 

Wildcats and one-off rounds are not listed here. To be in the list the worst calibers list, a cartridge has to be introduced with an eye for the commercial market. 

Click here for The Top 10 Worst Guns Ever Made

In no particular order, here are the worst gun calibers around. 

.45 GAP

"The .45 GAP (Glock Auto Pistol) is a solution to a problem that never existed," said Abraham Baldwin College history professor and weapons enthusiast Jim Galt-Brown. Exactly why Gaston Glock created the .45 GAP is a matter of some debate. Perhaps he wanted a round with the Glock name attached to it. Regardless, the .45 GAP handgun is only made by Glock. The round itself is a .45 ACP shortened to a 9mm length. It uses a small rifle primer, yes, it does. 

Shooting the .45 GAP from a .45 ACP auto is not advised because both rounds headspace on the case mouth and the brass for each has significant differences in the rim. Among the worst handgun calibers ever, this may be No. 1. 

The Dart 

The Dart is actually a series of worst gun calibers, .10, .12, .14, 17 and .20. W. Eichelberger actually produced a lot more rounds with his name attached. Several of the Eichelberger line are resized .22s, necked down to accept a smaller projectile. W. Eichelberger is listed in several of the US Patent Office "Official Gazettes" as the inventor of gun-related items at the turn of the last century. 

Sub-.22 Rounds 

Several sub-22 caliber rounds came out over the years. The most common are the .10 Long Rifle, .10 PUP, .10 H&R Magnum, .10 Squirrel, .12 Long Rifle, .12 WRM .12, Cooper .12, H&R Mag .12 Carbine and the .12 Squirrel. Reed's Ammunition & Research has some load data and consumables for some of these rounds. 

22 Remington Jet

22 Remington Jet

 The 22 Remington Jet is the second-oddest looking round in this list. The shoulder is nearly as long as the case body. It certainly has the longest taper of any centerfire round. It came out in 1961 as a handgun round. The last mass manufactured gunfire this round came off the factory floor in 1972. 


Both a firearm (rifle and handgun) and ammo, the Gyrojet started out as a 13mm round. After the Bureau of Alcohol, Tobacco and Firearms said that put it into the destructive weapons bore size, the company reduced the projectile size to 12 mm. 

The Gyrojet is literally a miniature rocket. The entire thing, the whole case, leaves the barrel when fired. Rocket exhaust comes out ports on the "primer" side of the round's head. 

Caseless ammo 

An effort to produce caseless ammo led to the 223 VOERE. Why? Weight mostly. Caseless ammo should be lighter so soldiers could carry more. 

The problem is a caseless-ammo rifle will not fire anything else without a visit to a gunsmith to change a lot of parts. Regular firearms will also not fire caseless ammo for the same reason. 

Forward Defense Munitions is trying another caseless rifle and ammo. If weight is the primary issue, then size and space are to be in second and the third place. 

2mm Kolibri

The 2.7mm Kolibri semi-auto is the world's smallest semi-auto handgun. The ammo is actually centerfire. It is the perfect self-defense round if you are being attacked by a rabid Alaska mosquito or a charging field mouse. For anything else, the impact of three-foot pounds of energy probably won't be noticed. It is not the world's smallest handgun. That title goes to the Miniature Revolver C1ST. Forgotten Weapons has a video on the Kolibri

The Kolibri is now a collector's item.

Super tiny handguns have to be among the worst handgun calibers ever. 

.32-20 Winchester

The .32-20 is on the list because it is obsolete. Wide Open Spaces calls it "the largest varmint round to ever come down the pipe, but it's not quite as big as it sounds." As with many older cartridges, the last two numbers are the black powder charge, 20 grains. 

While innovative when introduced, the .32-20 is long since eclipsed by better, faster and flatter-shooting varmint rounds. It has some following in cowboy-action shooting circles. 

Other rounds?

Got suggestions for the worst-cartridges ever list? Let us hear from you.

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