It's hard to say if more adult air gun shooting is done indoors or outdoors at the present time. As noted earlier there are certainly plenty of reasons for shooting indoors. However, few field activities offer any more relaxation and enjoyment than shooting an airgun. The relative safety and quiet of fine airguns allow you to do with ease things that might not even be possible with a firearm. You don't have to have formal targets or live game to enjoy a day in the field. Acorns, pebbles, twigs, icicles, etc. all become satisfying casual targets. With a little imagination, you can supply a whole range of easily obtained, inexpensive plinking targets: Neccos, aspirin or saccharin tablets, dry clay balls, hard white mints, soup crackers, etc. all give a satisfying disintegration when hit. Use of such targets can help develop the idea of plinking as an acceptable, non-destructive sport. These targets are even biodegradable! One clever idea for real sharpshooting is to put out ripe meat as bait and shoot down the flies or "yellow jackets" which soon buzz around it. If you prefer slower targets, try baiting snails! At greater distances beverage cans will always be popular, but you should try some other targets like "indoor" golf balls, swinging targets, suspended bells, etc. (A few cautions: Be sure that pellets missing your targets will land safely. Be careful of ricochet; shooting glasses or tempered eyeglasses are a must for anyone within the vicinity of any gun. Please pick up used cans and don't litter the bottom of streams and lakes with sunken cans.)
Eliminating rodents, destructive and fouling pest birds like English sparrows and starlings, and even things like locusts and grasshoppers, can also be plenty of sport! As a good outdoorsman, you would, of course, learn which organisms are harmless, or even beneficial, and avoid the temptation of plinking at them. The selective control of pests by the adult use of airguns, rather than the indiscriminate use of traps and poison baits, can be of real ecological value.
Serious shooters enjoy seeing how well they can shoot with a precision airgun at various field distances. Some fire all four positions; others go to the extent of firing from a bench rest. Using a super tuned sporter or a match rifle under ideal conditions, it is entirely possible to fire 9 and 10 shot groups which could be covered with a nickel, even at 50 yards or so! Bench rest shooting is the ultimate test for shooting equipment, ammunition, and ballistic information. However, do not use firearm bench rest methods for airguns. The forearm, especially on spring piston airguns, should be supported by the shooter's hand.
The use of airguns for small pest control depends largely on knowing what is happening at the point of impact. Information from the ballistics section of this publication can be useful, but it must be extended to field distances. Those shooters, and even some writers, who are still stuck in the "firearm mode" of thinking would say that the more power that you can deliver to the live target the better. However, with at least minimally adequate power the most important thing is to deliver the pellet exactly. When working with airgun energy levels a well-placed head shot is called for on most pests. Some forms, such as crow, are better taken with a squarely placed mid-chest shot. In any case, the lethal area is quite small, perhaps only 1/2" to 1-1 /2" in diameter. As an example, consider squirrel shooting. Examination of the accompanying tables show that, depending on caliber, you must deliver about 3 EP to a roughly one inch lethal area. The energy/velocity and accuracy tables show that even a .177" match air rifle delivers sufficient velocity up to perhaps 50 yards but that a hit in the area is extremely unlikely beyond that distance. Thus, potential accuracy is ultimately the limiting factor, and your ability to get that accuracy depends on practice and good equipment. Don't minimize the importance of good equipment; no matter how well or poorly you shoot, better sights, a more accurate gun, a better trigger and better pellets will tighten your groupings.
While a scope sighted, match rifle in the hands of an expert may be the best airgun combination for most small pests, the majority of shooters would probably be better off with an accurate, high power sporter. These guns are suitable for larger organisms; their pellets are less easily diverted by wind and leaves, and have flatter trajectory and better penetration. Round or pointed head pellets are the standard for pest shooting, but flat headed match pellets are often used for taking lighter animals. Match pellets deliver a little less lead but their greater accuracy at close range and their greater impact area is often an advantage. Greater ballistic drag does give match pellets less velocity (and less flat trajectory) at field distances as the table shows. Hollow point pellets are extremely effective in delivering maximum impact and the key point in airgun hunting is not muzzle energy, but how well energy is carried out to the prey. The energy/velocity table shows dramatically how heavier, larger pellets keep their energy. The clear winner in energy retention and ballistic efficiency is .25 caliber. Thus, trajectory drop with the bigger, heavier pellets is far less than might be expected. The .25 Crow Magnum, sighted in for 50 yards, keeps that powerful pellet within 2 inches of line of sight to over 55 yards! All factors considered, .20 caliber is probably the best all around choice, with a high power .25 being a good second, or even first, choice for the field.
You need a simple system for estimating where your pellet will hit when hunting. The excitement of the hunt and the difficulty of accurately estimating distance make complex systems useless. An effective, simple system involves sighting in your preferred gun/pellet combination for their maximum effective distance-your "Basic Field Distance" (BFD). You can determine your BFD's by experimentation. The BFD is the distance up to which the pellet has not been more than two inches above the line of sight. For a top power Beeman R1 in .177 or .20 caliber the BFD will be about 50 yards. The pellet will pass up over the line of sight from such a scoped rifle at about 8 yards, then go over the line of sight not more than two inches before it comes right down to the line at about 50 yards, and then be about 2" low at 55-58 yards. Thus you simply sight in, roughly and easily, at about 8 yards and fine tune your sighting at 50 yards. Practice (and practice!) estimating how far 50 yards is. At close ranges and for shots of about 50 yards, your sights should be about centered on the desired point of impact; at middle distances your sights should be about 1 to 2" low. Since you really can't estimate the difference between 50 and 55 yards, and the drop is so great over 50 yards, 50 to 55 yards should be considered your maximum practical range. For a .25" caliber R1 the Basic Field Distance is about 45 yards; the maximum practical range is about 50 yards.
Point of impact may be changed by many factors. Low temperature is often blamed for a lower POI, but humidity is probably the more important, but less suspected, factor. Higher humidity usually means a higher POI, but humidity is often low at low temperatures, especially temperatures below freezing. And all shooters should remember that shooting steeply upward, or downward, will result in a much higher POI.
Don't overlook careful, intelligent stalking as one of the most interesting parts of the field use of airguns. Getting close enough to small pests for the necessary exact shot can provide the excitement of a big game hunt in a setting much closer to home. Camouflage, low-profile stalking, and patient stands can be as useful in suburban field airgun shooting as they are in wilderness shooting.
Squirrel, Starling, etc.: Carefully practiced head shots are necessary. Stalk closely and use a scoped match rifle or use a scoped, high accuracy sporter.
Rats: A skilled shooter with a match rifle can make the necessary head shots to about 30 yards. Generally a high velocity sporter would be preferred.