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The Trend Towards Larger Caliber Airguns

Posted by on April 29, 2018

About a year ago I wrote an article for Airgunner in which I asked, Is the .30 the new .25? I was looking at the reasons hunters used the .25 caliber, and discussing whether the .30 was a better choice than the .25 when measured against the same criteria. The intention of this article is to take closer look at why so many shooters on this side of the pond are moving to larger caliber shooting rigs. Note that I’m not talking about the very powerful big bores shooting cast bullets, but rather the major calibers shooting Diabolo style pellets.

A compact .25 that is accurate and powerful is a great small game hunting gun that will let you take a predator or hog if the opportunity comes up!

This is not an argument of whether a legal or FAC power is better, rather a simple statement of fact that there are more high-powered airguns being manufactured than ever before. In the U.K. it is possible to purchase and use high power airguns, and the question of whether an FAC gun provides the shooter any advantage becomes an important one. In north America however, where there are few or any limitations on airgun power and the potential market is huge. For this demographic it’s fair to say most shooters and hunters own more than one firearm, and for these shooters even an FAC rated air rifle appears to be low power. I know very few airgnners that shoot sub 12 fpe guns here, even if they focus on springers.

Regardless of the power plant employed, if you are limited to 12 fpe, larger caliber pellets become less viable. Shooting a .25 or .30 caliber at 12 fpe would result in a pellet trajectory akin to pitching a shotput underhand, with such a range dependent shift in the point of impact you’d need a ballistic calculator to know where the pellet would hit along a 40-yard flight path. But if unconstrained by power restrictions, the logical design step when moving to a larger caliber is to increase the power output of the rifle.

A .25 will let you take head or body shots, and stretch out further than you could with a .22.

If I want to use a 25 grain .25 caliber pellet in a “Legal” limit rifle, the velocity would have to be kept at around 450 fps to generate 11.2 fpe. Such a slow-moving pellet would be of limited use outside of a dozen yards. On the other hand, use the same pellet but keep the velocity at around 950 fps, generating an energy output of 50 fpe, and it’s a completely different story. This pellet is now zipping along with a flatter trajectory than an 8 grain .177 pellet with a muzzle velocity of 800 fps (generating 11.3 fpe).

Since gravity works at a constant rate, the trajectory is a product of the velocity at which the pellet travels. So, remove the need to limit the power output the logical step is to increase the velocity and resulting power output as caliber is increased. But there is more to it than the muzzle velocity, the smaller caliber pellets generally have a poorer ballistic coefficient and are always much lighter. The effect of resistance on lighter pellets in flight is that they shed velocity more rapidly. This means that even if the .177 pellet was launched with the same muzzle velocity as the much heavier .25 caliber pellet, at 50 yards the larger pellet would be traveling at a higher velocity than the lighter. The trajectory of these two pellets at closer range would be similar, but the drop would be greater in the light weight smaller caliber pellet at longer ranges.

The intrinsic accuracy of the two pellets might be fairly close: but the need to compensate for pellet drop with the smaller caliber pellet makes it harder to shoot accurately, especially under field conditions. This is one of the reasons that many shooters competing in long range target events, as well as those hunting in conditions requiring longer range shots, have been moving to .25 and even .30 caliber rifles in recent years.

Another reason you’ll hear given for the .25 caliber preference, is that the heavier pellets, even though they have a larger surface area, are less effected by wind. Whether this is due to the weight being less influenced by wind, or the fact that at greater distances the heavier pellets are moving at a higher velocity and thereby reducing the time available to exert influence, I don’t know. But my experience shooting on paper and on game leads me to believe this is true, though let me add that if the wind picks up to the point its pushing your pellet off course, it’s time to either move your range in closer or quit shooting.

So far I’ve focused on the trajectory of the larger caliber pellet, and not the power delivered on target. For target shooting this is not a high priority, for hunting applications it may or may not be, depending on several factors. If hunting 1-2 lb. cottontail rabbits on one of my farm permissions, where most shots are inside of 40 yards, a 50 fpe .25 caliber rifle is not necessary. However, if pursuing a 10 lb. jackrabbit at 75 yards, the powerful .25 caliber pellet will be much more decisive in anchoring my quarry. In both scenarios, a more powerful and larger caliber gun gives me the latitude to effectively take both brain and heart/lung shots.

One other consideration is that for many of us hunting in North America, there are more species to hunt that found in many regions. An airgun hunter might have the opportunity to hunt smaller cottontails or larger jackrabbit, large body animals such as turkey or raccoon, or quarry such as prairie dogs that require long range shooting. A .22 could be used for all of these but is a more marginal performer with the larger animals or at longer distances. And while a powerful .25 caiber might be overkill for a squirrel or rabbit at closer range, it is effective, and allows me to have one gun that does it all.

To this point I’ve spoken primarily about the .25, but many shooters are moving to the .30 caliber for many of the same reasons. As far as competitive shooting, some events set .25 caliber as the maximum in the standard caliber class, and the .30 as the gateway into the big bores. My primary reason for moving to the .30 caliber centers more on the need for a rifle I can use for the larger game sometimes encountered on small game hunts. I am going out on a prairie dog shoot next week in South Dakota, and there will be an opportunity to do some long-range shooting on paper and then on live quarry. I will use this opportunity to get my thoughts in order on where the .30 caliber fits into my shooting worldview then, and hopefully Phill will let me do a follow up afterwards!

What has made this discussion relevant, is that there are now many outstanding guns being offered in both .25 and .30 caliber, I’m using the Daystate Renegade, Brocock Bantam, FX Wildcat, and Hatsan BullBoss in these larger calibers, and importantly, have had the opportunity to shoot them all in .22 as well. I will make two general statements: in every instance my long-range shooting (on paper) has been better with the major calibers. And on game (granted this is anecdotal) my impression is that kills have been quicker and cleaner, especially on body shots and at longer range.

Let me windup by saying that the rationale for migrating to larger calibers is situational, but I think for North American hunters there is a lot to think about, for me the .25 has become my all around favorite small game caliber.

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