by B.B. Pelletier

Announcement: Gavin Twigger is this week’s winner of Pyramyd Air’s Big Shot of the Week on their facebook page. He’ll receive a $50 Pyramyd Air gift card.

Gavin’s said this about his submission: “This is what HAPPY looks like. Cheers Pyramyd Air! Great deal, great job. Hopefully soon, I’ll show you the rabbit that’s been digging up my yard.”

Today, we’ll start a large report that I’ve wanted to do for quite some time. It’s based on the belief in the firearms community that a .22 caliber CB cap is just as good as an air rifle for eliminating pests.

By “good” I take four things into consideration: accuracy, power, cost-effectiveness and discharge sound.

Before I started this test, I’d read a lot of shooting forums and came away with the observation that very few shooters really know what CB caps are and how well they do or don’t work. Every discussion I found was centered on using the cheapest approach to pest elimination, then projecting the CB cap on it as the solution. I also discovered that the people who were doing the talking considered Gamo spring rifles to be the most expensive air rifles around. They also were comparing CB caps to Crosman 1377 pistols and 1077 rifles.

With that much confusion and misinformation, I felt honor-bound to test CB caps against real, worthy air rifles — not to shame the CB caps, but to set the record straight. In this test, I’ll be pitting several .22 rimfire rifles shooting CB caps against an AirForce Talon SS with a .22-caliber, 24-inch barrel. It’s the same rifle I tested for you several weeks ago in the three-part series titles What would BB do? In fact, that report series was actually one of the preambles to this test.

Brief history of the CB cap
The CB cap has a history that dates all the way back to the 1840s. At that time, the percussion cap was relatively new, having been in existence less than 40 years and in general use less than 20 years. By 1840, it’s safe to say that percussion ignition had all but replaced the flintlock except for a few shooters who held out for very specific reasons.

In Europe, someone had the idea of using just a percussion cap itself to power a small, lightweight lead ball for very close-range shooting. By 1845, Flobert was making and selling these bulleted breech (BB) caps for small, inexpensive guns. Some guns were rifled, others were smoothbore and a few were very fancy, indeed. They were available in a number of metric sizes, with 6mm, 8mm and 9mm being among the most popular. In these Flobert cartridges, the priming compound was the only thing providing the propulsive force for the projectile.

In 1855, Rollin White patented the bored-through revolving cylinder, and the startup company of Smith & Wesson used his patent to create the first .22-caliber revolver that used their new proprietary .22 rimfire cartridge. This small cartridge would later be known as the .22 Short, but at the time it was the only .22 rimfire cartridge around so it was just called a .22. As an important deviation to the Flobert ammunition, this cartridge did contain a small amount of gunpowder! Remember, at that time, all gunpowder was what we call black powder today.

The history of the CB cap and .22 rimfire cartridge is worthy of an entire book, but I’m going to skip a lot of that. Some time after the BB cap was created, a cartridge with a little more priming compound was created to launch a heavier conical bullet. Instead of a round ball, which is ballistically inferior, this new conical ball cap, or CB cap, shot a heavier projectile that also had a slightly higher ballistic coefficient.


It’s confusing, because cartridge makers also refer to CB caps as zimmer ammunition. They’re not the same as 4mm zimmerstutzen ammunition.

On a parallel path of development, but not part of the .22-caliber rimfire cartridge development, was the creation of the zimmerstutzen or parlor rifle. It initially used separate percussion caps to power a small lead ball in the same way that Flobert cartridges worked, and by the latter part of the 19th century the cap and ball had been joined into the now-familiar shape of a rimfire cartridge. These small rounds look like BB caps, but they’re smaller in diameter and do not play a part in the story I’m telling.


Zimmerstutzen ammo still comes as both fixed rounds (right) and separate components.


The 4mm zimmerstutzen round (left) is dwarfed by the .22 Long Rifle cartridge. The two do not compete in the same sports, nor are they used in the same guns.

By the early 20th century, there were both BB caps and CB caps mixed in amongst the other sizes of .22 rimfire rounds, of which there were many more than we see today. By this time, the BB cap had standardized, more or less, into a tiny self-contained 6mm cartridge with a lead ball crimped in the end. Because it was so close in size to the .22 rimfire bore diameter, the 6mm BB cap was commonly shot in .22 rimfire guns, though it had to be handled manually because it was too short to feed through any repeating mechanism other than a revolver cylinder. Later on, I’ll be showing you some 6mm BB caps in this series and even shooting them for you, but right now I want to remain focused on the CB cap.

Is a CB cap just as capable as a good air rifle pellet?
That question is the focus of this test. I want to give CB caps all the advantages possible to let them show their best face, because the airgun they’ll be compared to is already a known performer.

The test rifles
I initially decided to use the following four rimfire rifles in the test.

1. A customized Ruger 10/22 that has a tuned trigger, a tighter target-spec. chamber, closer headspacing and a couple other improvements that do not affect accuracy, such as an improved magazine release. The rifle is scoped with a Centerpoint 8-32x56AO scope.


This 10/22 looks stock, but a lot has been done to make it a better shooter.

I chose this rifle because it’s so commonly available. It isn’t the most accurate .22; but with the modifications my rifle has, it’s more accurate than a factory 10/22 and able to hold its own against other good, contemporary rimfire rifles.

I also have a 20-inch Butler Creek bull barrel and custom stock for this rifle, and I can swap those for even better performance. That gives me not one but two different 10/22 rifles to use for testing.

2. A Remington 521 Junior Target rifle was also selected. The 521 is very accurate, yet it’s not in the same class as a Remington model 37 or a Winchester model 52. In short, it’s an accurate bolt-action rifle that the average guy might own. You could equate it to a modern Savage or CZ bolt-action. The sights are a Lyman rear aperture target sight and a model 17A globe front sight with ring insert.

3. A Winchester Winder Musket chambered in .22 Short caliber was the final choice for this test. This is a special version of Winchester’s popular 1885 Low Wall model. The Winder was developed for the junior target shooter of the early 1900s. It was considered to be one of the best junior target rifles of its day and was even purchased by the U.S. Army for their marksmanship training. Because it’s chambered for the Short cartridge, I’ll be able to take advantage of the CCI CB Short cartridges that might not work as well in rifles that are chambered for the long rifle cartridge. The sights are a special Lyman rear aperture target sight and a Lyman 17A front sight with ring aperture.


Winchester’s Winder Musket is a fine target rifle from a century ago. This one still shoots well.

The pellet rifle
I’m shooting my AirForce Talon SS with 24-inch, .22-caliber barrel and the bloop tube that was reported in the series What would BB do? You’ve already seen this rifle turn in a 10-shot group that was smaller than a half inch at 50 yards, but I’ll be shooting it, again, on the same days I shoot the CB caps to keep the conditions the same for every projectile.


The one pellet rifle in this test is my Talon SS with 24-inch barrel and bloop-tube silencer.

CB caps currently available
CB caps come and go from the market, and more have gone than have come in recent times. When I made my ammo purchase for this test, all I was able to buy were CCI CB Longs that have the cartridge case of the Long Rifle with a shorter and lighter bullet, CCI CB Shorts that have the Short case and the same bullet as the Longs, Aguila Colibris that have the Long Rifle case and a smaller bullet, Aguila Super Colibris that have the same case as the Colibris but offer different velocity, and RWS 6mm BB caps. All of these cartridges have priming only inside the case. None contain any gunpowder.

In recent years, I’ve been able to buy CB caps from other makers such as Eley; but when I made my ammo purchase this time, these were all that were available in the U.S.

The premise
I’m testing whether it’s reasonable to assume that a .22 rimfire rifle shooting CB caps can perform as well as a good pellet rifle, with respect to accuracy, power and quiet report.

The test
I decided to test all the guns for accuracy at 25 yards and 50 yards with 10-shot groups. For sound, I’ll use my ears, plus those of whatever witnesses are available. I’ve already done some of this, and it works well. You don’t get a number, but you can tell when something is louder or quieter than something else. I’ll get velocity from the chronograph, of course, and cost will be calculated on the ammunition, alone. I won’t factor in the cost of the guns, because nobody will ever have exactly the same guns as someone else. I want this to be representative of what a shooter would encounter if he decided to pit CB caps against a good pellet rifle, but there will always be differences in equipment.

First day at the range — a lot is learned
Things seldom go as we plan, and nothing shows that as clear as a day at the rifle range. For starters, I discovered that the semiautomatic 10/22 would not feed any of the CB cap ammo from the magazine — even when I manually cycled the bolt. Two thirds of the time the cartridge failed to enter the chamber, which caused me to stop and clear the gun before proceeding.

After a number of such misfeeds, I unloaded the magazine and loaded each cartridge into the chamber by hand. That’s not easy to do with a 10/22 that doesn’t have an automatic bolt hold-open feature. It’s possible, just not easy.

Still, I managed to shoot two groups of 10 rounds at 50 yards. One was with Aguila Super Colibris and the other was with CCI CB Longs. The Aguilas landed on two different targets for a group size in the range of 12 inches, and the CCIs landed in a group that measured just under seven inches.

Then, I tried the CCI CB Longs in the Remington 521 and got a group of 10 in exactly four inches. I may have tried the Super Colibris in this rifle, as well, but I have no target to show for it, so I think I didn’t.

The Talon SS shot three groups of 10 with JSB Exact Jumbos domes weighing 18.1 grains. The best group measured 1.25 inches, while the worst measured 2.1 inches. One group of JSB 15.9-grain Exact domes went into 1.37 inches.

Where do we go from here?
I’m just getting started with this test. It’s the research for a feature article I’ll write for Shotgun News in November, and I’ve already been to the range two times. I’ll have to write a special summary report when this test is completed to make sense of all the data.

I would like to hear what you guys think. Especially, those of you who have experience shooting CB caps in rimfires. I’m not sure where this test will take us; but I already see things I never would have expected, so I think we’ll all learn something from this.