After all these years of hunting, shooting with, and writing about Airguns, the most frequent question I get is “what caliber is best”? The answer I give is probably not the crisp and clear response that is hoped for, because there are many variables that come into play. Personal preference aside; it depends on the type of gun, the power levels being used, what the gun is being used for, what’s available in the gun model the buyer wants. I’ll tell you about my personal preferences and why, then take a bit broader look at the question.

The right caliber depends on the job you need done. Right now you can get diabolo pellets ranging from .177 to .357!
My preference in PCP calibers for small game has generally been a .22. That is not to say there is anything wrong with a .177 or .20, however the .22 has a breadth of application that is hard to beat. Most PCP designs generate the optimal power for the larger pellet, the .22 is accurate (as a rule), and it carries well for longer range shots (compared to the smaller pellets). A round nose or a hollowpoint has good terminal performance on small pest species, but a heavy pellet in a more powerful gun will also let you step it up on larger game such as a groundhog or raccoon.
On the other hand I don’t have such a strong preference for the .22 in springers and will often shoot .177. In springers, guns set up for .177 may have a lighter cocking effort than a larger caliber, I think they recoil less, and from a practical point of view, this is the most common caliber for these guns. I also tend to limit my shots to closer range out of a springer, because I don’t shoot them as well as PCP’s, so I’m not as concerned about long range capability. One of my all-time favorite rifles, which I’ve frequently spoken of, is the little Beeman C1 carbine. I have taken more game, ranging from ground squirrels to very large jackrabbits with this 14 fpe .177 than any spring piston gun I’ve ever owned. The .22 caliber version of this particular rifle, did not appeal to me, I didn’t like the shooting characteristics, the accuracy was only OK, and the trajectory was loopy. But in other springers I found the exact opposite, with better accuracy in the .22 over the .177……. So sorry to those wanting a black and white answer …. It depends.

I’m using the .25 a lot these days for my small game guns. But if you like the .22, no problem there either. I save the .177 for the smaller stuff, but that’s just me. Lots of small game falls to the .177, but I hunt in some thick brush and want a decisive hit that anchors my quarry.
The reason I’m not a bigger fan of the .20 is simply a question of logistics; pellets are harder to find, there is a more limited selection of designs, and fewer guns chambered for it. And when you do find one, you may have to pay more for it. But that doesn’t mean there is anything wrong with the caliber, and many ways it is a good compromise getting higher velocities than the .22, longer carrying range than a .177 with a flatter trajectory than a .22, and larger wound channel than the .177. If you can find it in the gun you like, and have a supply of the pellet it performs best with, this can be a great option for a springer especially.
There is of course the .25 which has been the biggest of the Diabolo pellets. But recently we’ve been presented with more choices; the .30 and .35. I love these calibers in the right gun (generally a PCP) for the right game. Before Talking about where these are favored calibers, let me say something about big calibers in springers. There are a few .25 caliber springers on the market, and recently I’ve been using a newly released .30 caliber springer. These guns would not be my recommendation if it was to be your only rifle, or if the intended use was anything other than hunting. They are hard to cock, kick like a mule, and take a lot of practice to be accurate with. They are specialty guns for a niche market. And again while the bigger calibers in spring piston guns would not be my usual recommendation, if you have a hunting application requiring a moderate amount of power and the generation of a big hole, there is nothing wrong with the option. They are actually fun to shoot …. In moderation!

The .30 is good for smaller predators and small game. A good crossover caliber, and if you get a shot at a yote, take it.
But if we shift the discussion to large calibers in PCP’s the story changes; I mentioned that in the past my PCP preference has been the .22, but for much of my small game hunting I’ve been moving to the .25 over the last few years. In a 45 fpe gun it works great on squirrels and rabbits, but if an opportunity presents for a fox or a raccoon it’s still a decisive round. And in the last couple years the .30 has been impressing me. Like the .25 it bridges the small and medium sized quarry, but skews a bit more towards the larger stuff without being ridiculously over powered for smaller targets. I’ve taken squirrel, rabbits, raccoons, bobcats and coyote with this caliber in a 80 fpe gun.
The .35 is the new kid on the block, and it is impressive …… For the right application. It would not be my choice for bigger game such as deer or hogs. A .35 cast bullet out of a 200 fpe gun is acceptable, but the .35 Diabolo in a 100 fpe gun is not a big game gun. It is however a great predator gun; I’ve taken bobcat, coyote, javalina, and turkey and it’s a great option for this type of quarry. It’s way too much for small game though.

The .35 was my go-to for suburban coyote, gets the job done, and is just about perfect for those inside of 50 yard shots, body or head.
So to distill my message from this rambling post; for a small game springer .177 or .22 work for me. For my small game PCPs I like the decisiveness and flexibility of the .25. If I am going to bridge small game to predators the .30 is a good option, and if I won’t be heading south of predator sized game the .35 works a trick. And note that for every one of these “rules of thumb” there are exceptions. So use what I’ve said as a guide line bout don’t be too rigid, the main thing is that you want a gun you like, that has its sweet spot where you’ll do most of your shooting, but has the flexibility to cover you in those corner cases.
Other stuff
In Japan right now, but when I get home, will rest up for a few days then off to Texas for 11 days of hunting for small game, hogs, predators and black buck! This is the start of a very active hunting period for me, booked for 2-3 traveling hunts per month throughout the rest of the year! Going to South Africa, Mexico, and maybe Patagonia as well! Check in often, I’m back on track with updating the blog, I hope you’re all getting out shooting and enjoying the tail end of winter!
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