by Tom Gaylord
Writing as B.B. Pelletier

diabolo pellet
The diabolo pellet exists in four smallbore calibers.

This report covers:

  • Smallbore calibers
  • Before diabolo pellets
  • Birth of the diabolo
  • Ideal for plinking
  • Highest velocity
  • Velocity wars
  • Target shooting
  • Field target
  • Summary

Sunday while I was walking through the hall in my church a man stopped me and said, “You know a lot about airsoft? You’re the grandfather of airsoft?” He had been talking to our youth pastor who works part-time at AirForce Airguns and he was trying to remember what he’d just heard.

Most readers can guess my response, but once we were on the subject of airGUNS, he said he needed a good air rifle — something to use on pests. He told me that he was aware such guns cost as much as $100 or even $125, and what would I recommend?

What I would recommend is an education, but of course I didn’t say that. We have all been where he is now and we had to learn from someone! That started me thinking about the basics. A couple weeks ago I completed the series on How to mount a scope. There were plenty of basics in that series, but we also went into some of the more advanced principals. I thought that would be a good approach to use for pellets, as well. Let’s see where this goes!

Smallbore calibers

There are four smallbore airgun (pellet gun) calibers — .177, .20, .22 and .25. I’m going to leave BBs out of this discussion because they deserve a series of their own — and they will get one. In this series I will look at each smallbore caliber on its own. Today I’ll begin with the .177.

Before diabolo pellets

The .177 dates back to the early 1900s, along with .22 and .25 calibers. Before that there were slugs that could be called pellets, though they weren’t in the same class as the diabolo we know today. There was the cat slug, the burred slug (which is the same as the cat slug but by a different name) and the felted slug. All were solid lead with some kind of tail that increased drag.

Cat slug

felted slug

Birth of the diabolo

Sometime around 1905, the diabolo pellet was born. There aren’t solid histories of this anywhere that I know of, but from pellet boxes we know that the diabolo existed before 1909. And there were British trials conducted with diabolos in 1908, according th Walter. I say 1905 because that’s when the H The Lincoln rifle that was to become the BSA rifle was born.

The .177 was right there with the earliest true diabolo pellets. At the time it wasn’t the favored caliber because of the small size of the pellet. It was found most often in ladies model airguns. But that didn’t last. Even back then it was obvious that if all you wanted to do was shoot or plink, a less expensive pellet was best, and even back then the .177 was cheapest because it used less lead. 

Before we leave this topic of diabolos I want you to understand that at the time it was not clear they would be the pellet design of choice. Several other designs were tried at the same time. Diabolos just outlasted all the others. Even today some solid pellets are attempting to break back into the market. But the diabolo reigns supreme.

Ideal for plinking

This is the first big advantage of the .177. They are the ideal plinking pellet because they use less lead. Less lead means a cheaper pellet. To offset the difference in cost the larger calibers are now putting fewer pellets in a tin. A typical .177 tin still holds 500 pellets, where a typical .25 caliber pellet tin holds — well there really isn’t a “typical” 25-caliber pellet tin. They hold from 83 on the lower end to 350 on the upper end.

If all you want to do is shoot at things and watch them move or make noise when they are hit, the .177 is the best way to go. Oh, the heavier pellets will make more noise and move things around more, but the .177 gets the job done.

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Highest velocity = best-selling

Velocity is a strong selling point for airguns in the lower price category, and that is the category that sells the largest number of pieces. The profit margin per piece is usually the lowest, but the volume that is moved more than makes up for it.

What that means is the most “popular” (best-selling) airguns are going to be .177 caliber. More airguns sold translates to more pellet sales in that caliber, with the result that the .177 caliber pellet is the best-selling of all four smallbore calibers.

Velocity wars

The high-velocity wars began in the 1970s — about the time that personal chronographs became affordable. Prior to the 1960s if you wanted to know how fast a pellet went you had to enlist the services of a commercial laboratory. W.H.B. Smith who published Smith’s Standard Encyclopedia of Gas, Air and Spring guns of the World in 1957, used the services of the H.P. White  chronograph — a device that occupied several rooms and used the services of multiple people. Its accuracy was one-tenth or less of what you can get from a hundred-dollar chronograph today.

Prior to that time Americans used pellet guns for pesting, while the rest of the world focused more on plinking and target shooting. In a few places, airguns were used for subsistence hunting and they favored whatever they could get that would do the job. The thousands of Crosman 101 pellet rifles that were bought by the U.S. Government in World War II, along with a million rounds of ammunition, were mostly given as gifts to influence tribal chefs in southeast Asia.

So Americans favored the .22, while most of the world liked the .177. The British also had the .25 caliber (6.35 mm) pellet at this same time but no powerplant was up to the task of launching it very fast. So it lagged behind the .177 and even the .22.

Target shooting

Ten-meter target shooting with airguns is an outgrowth of shooting 4mm zimmerstutzens that shot (and still compete today) at 15 meters. Like plinking, the size of the pellet makes little difference to accuracy when you shoot at paper, so the less expensive .177-caliber naturally dominated this category. However, the British, notable contrarians that they are, did make several target rifles in .22 caliber, and even Diana and BSF of Germany did the same. But all of this was before the world cup and finally the Olympics put their stamp of approval on .177. When they did that all the scoring gauges were standardized in .177 caliber (4.5 mm). Today the .177 caliber pellet is mandatory for national, international and world competition.

Field target

The far less popular sport of field target (millions compete worldwide in 10-meter target shooting, thousands in field target) also favors the .177 caliber, though it is not mandated. The reason it is favored is statistical rather than rule-based. In field target you shoot through a hole in a steel target at a moveable paddle that stands behind. If you hit the paddle and it moves far enough, the target falls and the shooter is awarded a point. But if the pellet strikes the steel target first as it is trying to pass through the hole, it pushes the target backward against the release mechanism. If the push is hard enough, even hitting the paddle with part of the pellet won’t be enough energy to drop the target. The result is no point.

Statistically, the .177-caliber pellet is smaller than all other calibers, giving it a better chance of passing through the hole without contacting the side. Or, if it does touch the side, the .177 is small enough that it has less chance of locking the target in the upright position. It’s a probability thing and competitors understand that the smaller pellet is the best choice.

In recent years the British field target power level cap of under 12 foot-pounds has been incorporated into the world-class rules and the lighter .177 pellets travel faster at the maximum permissible power than do heavier .20 and .22-caliber pellets. A faster velocity means a flatter trajectory that translates into improved scores for everyone. The bottom line of this discussion is the .177 caliber pellet is better-suited to field-target competition  than any larger caliber.

Hunting

If I don’t address hunting someone will complain. And you can hunt with a .177 caliber airgun. Doing so means your shot placement has to be perfect, as the tiny .177 projectile cuts a narrow wound channel. I don’t recommend the caliber for hunting solely , unless you allow for its shortcomings. Killing mice in the cellar would be preferable to hunting crows in the barnyard. If you want to hunt crows and .177 is all you have, go for it. Just don’t choose the caliber because the pellets are cheaper.

Summary

So .177 is the most popular pellet caliber for all these reasons. Can you think of any more?