Picking an air pellet

I hunt with a lot of differing rifles ranging from the diminutive .14 Walker Hornet to the awesome .35 Whelen Ackley Improved. But I have to say I still really like hunting with an airgun. I guess the reason is that I still enjoy the challenge of stalking close to my quarry with a rifle that needs a lot of skill to connect with your target. Air rifles fill a unique place in the British sporting world and can offer superb hunting potential when a firearm is inappropriate or when one wishes to work hard at bagging a rabbit for dinner. But that age old question of best calibre will surely rear its ugly head as to their suitability for varying quarry species and maximum range and accuracy potential.

Realistically there are four calibres to choose from .177, .20, .22 and .25” spanning a broad range of projectile sizes weights and potential benefits for any one given species or range that they may be encountered. However, true, non-certificated air rifles can only produce a maximum of 12 ft/lbs of energy (legal limit). This seems a paltry sum compared to a rimfire, which makes it especially important that pellet and calibre choice is critical to the quarry you shoot.

CALIBRES EXPLAINED

The .177 and .22” have served us well over the years but the .20 and .25 calibres are having a resurgence these days.

.177

The .177 (4.5mm) is the lightest and smallest with pellet weights ranging from 6.0 to 11.6-grains, which allows higher velocity than the other calibres within the legal limit. 7.0-grain pellets can travel 870 fps whilst 11’s achieve 700 fps and both generating no more than 12ft/lbs energy. The .177 is often considered a target calibre but actually it has potential over the larger .22 due to its higher velocity and therefore flatter trajectory. However it also has a smaller cross sectional area than a .22” (nearly 60% greater) and is more inclined to penetrate further. Useful, but it does not impart as much striking energy as would the larger .22!

.20

The .20” (5mm), a favourite in America as it combines good velocity and ballistic coefficient (BC) that retains energy down range, so hits hard like a .22 and shoots flat like a .177! Weights range from 9.0 to 15.5-grains which transcends the heavier .177 and many of the .22 pellets. This means that you can have the same weight as say a .22 in a smaller diameter but longer pellet. A typical 11.4-grainer can travel at 680 fps whilst a 14.3 grain can be pushed at 610 fps.  A little gem but as is seen later with the normal weight pellets there is little practical advantage over a .22 and the .20 only really comes alive in an FAC-rated rifle at over 875 fps.

.22

The .22 (5.5mm) has always been a hunters first choice and for good reason, it offers a large cross sectional area that transfers energy well into your quarry with adequate penetration. Weights vary from 12.0 to 21.0-grains and because it is probably the most popular calibre there is a huge choice available as well as rifles. Typically a 14.3-grainer is doing 600 fps whilst 21-grain heavies lumber along at less than 500 fps from a spring-gun. The heavier they are the more curved trajectory, which can be the .22s downfall at longer ranges. Still for every day use at sensible ranges it’s a good all-round performer.

.25

The .25 (6.3mm) has always held the moniker of ‘rat buster’ due to it being large and heavy and travelling at relatively low velocities compared to the other calibres but delivering a real thump at short range. Weights vary from 19.0 to 31-grains commonly there are some speciality lighter or heavier pellets as with all the above calibres, but there are fewer choices of manufacturers and rifles available. Typically a 19.8-grain travel at 480 fps and the big 26- grainers lumber along at 315 fps. Despite low velocities the big .25 has a real place in the British shooters armoury.

PELLET DESIGN

Modern day pellets are not always lead, non toxic or synthetic construction can also be encountered. This is also true with size as the head and skirt size must match your rifles bore dimensions to achieve best accuracy and velocity. Manufacturer’s bore dimensions can vary a lot. Most will offer each of their pellets in slightly differing dimensions; in .22 as the metric 5.50, 5.51 or 5.52mm so you can choose what best suits.

The most common style is the domed head, but there are also flat, pointed, hollow, and heavy weights all offering differing performances. Domed are good all-rounder’s and achieve better BCs for down range performance than most of the other designs. Flats are usually used for target shooting, but can also achieve good energy transfer on your quarry but at the sacrifice to longer range performance. Pointed would seem to offer the hunter better penetration but if it does not shoot accurately any advantage, if any, is lost. Hollow points due to the relatively low general airgun speeds do not expand as well as they would from a firearm.  The Heavy weights hit hard and carry their momentum forward to transfer their energy into your quarry.

I used a variety of guns to reflect a true velocity and energy figure that you may encounter. Temperature on the day will makes a difference from the same rifle too. Each calibre has its own merits. The .177, .20 and .22 retain good velocity levels out to 30 yards and what the .25 started with it retained well, but 20-25 yard is the limit in my view.

At beyond 30 yards the faster shooting .177 wins on trajectory compared to the slower/bigger .22 with the .20 close behind. So why has the .22 has always been more popular despite it retaining good energy levels? At 45 yards, maximum for a 12 ft/lbs. rifle, the .22 trajectory falls away fast, with a 30 yard zero the .177 is only -1.3” low whilst a .22 pellet at the same energy figure is -2.8” and at 50 yard it is double the drop of the faster .177, -4.4” inches as opposed to -2.2”. The .20 slips in rather nicely with a drop of only -2.7” at 45 yards so not that far behind the .22.  However at 12ft/lbs the .177 probably has the edge as it is not until you start shooting the .20 at FAC velocities that there becomes a much better advantage.

CONCLUSIONS

Calibre choice comes down to your preference and abilities and the range at which you are comfortable taking shots at. Also remember PCPs generally work better with heavy pellets. Spring-guns and gas rams willwork better with medium or lightweight pellets. For most shooters the .22 will harvest quarry up to 35 yards or so, but the .177’s flatter trajectory will make connecting with your target a lot easier up to and past this range.

The .20 at 12ft/lbs levels is probably only just a compromise between the two but lack of choice in pellets and rifles may be a drawback. The big old .25 just refuses to die and for sub 20 yard rats, feral pigeons or other vermin its sheer knockdown capabilities cannot be denied. I have shot all calibres in both 12ft/lbs and FAC-rated air rifles and it is amazing how just the slightest change in pellet construction or design can influence down range performance. The smallest advantage in energy and trajectory can be negated by poor marksmanship however.  Accuracy is key really and your rifle will tell you what it likes and then just practice and practice with it at all ranges and wind conditions to become proficient.