Airgun Expert and Air Arms Ambassador Matt Dubber tells us why the Air Arms S510 Xtra FAC is his chosen rifle when it comes to long range shooting.
With all the hype circulating through the forums and the media about ultra high powered air guns, I thought I’d do some research of my own. As someone with years of experience shooting everything from $25 no-name-brand springers to $2500 PCPs, I wanted to come to my own conclusions instead of buying in to the often sketchy claims of many advertisers. What’s the ideal long-range pellet? Does a higher velocity really increase my accuracy at long ranges? Which caliber is more ideal for long range shooting? These questions had been floating around in my mind for quite some time, and I was determined to find the answers.
I began with a simple Google search, and came across a number of articles and posts by Tom Gaylord, or “B.B. Pelletier” as he is known on the Pyramid Air Forums in the US. This guy had done some serious research on the topic of pellet stability and how velocity can affect accuracy. Through experimenting with different rifles, different calibers, different pellets and different velocities he had been able to make some interesting discoveries, and in doing so busting plenty of myths! (But I’ll get to that part later).
One of the primary concepts he kept referring to was “The Transonic Zone”, “Trans” meaning Through, and “Sonic” meaning Sound. I learned that projectiles passing through the sound barrier would experience forces impossible to predict, causing instability, and as a result – loss of accuracy. Since the speed of sound is approximately 1130 fps at sea level, I immediately came to the conclusion that any rifle with a muzzle velocity higher than 1130 fps would not be ideal. But here’s the catch – Because of the shape of most pellets, air is slowed down or sped up as it passes over the head and skirt. For this reason, the transonic zone is defined as the velocities between Mach 0.8 and Mach 1.2 – Your rifle may be launching pellets at 950 fps and still be experiencing the effects of supersonic travel.
I decided to do some tests of my own. I set out a number of targets at 25m, and a number at 50m. I then shot a number of 10 shot groups with my Air Arms S510 Xtra FAC using JSB Diabolo Exact 8.4gr Pellets, adjusting the power between each group.
At the lowest power setting the S510 Xtra shoots these pellets at about 600fps – well below the transonic zone. At full power, I was getting chronograph readings over 1000fps – well into the transonic zone. If the theory was correct, I should see a loss of accuracy as the velocity passes the 900fps mark.
At 25m, I saw no loss of accuracy at any power. All my groups were well within a centimetre – pellet-on-pellet. the 50m groups, however, were a different story. I found the groups shot at really low velocities (600 fps and 700 fps) did not fare very well. They just weren’t able to resist the slight breeze and the slight velocity inconsistencies between each shot. The groups shot at 850 and 900 fps were spot on – The increased velocity and flatter trajectory meant that external factors did not have as much influence as the previous groups.
The last two groups, at 950 and 1000 fps respectively, weren’t bad. There were decent groupings, but there were a number of flyers that could not be ignored. “Not bad” is not acceptable. “Not bad” could be the difference between wounding an animal and cleanly killing it. I had come to a conclusion.
In a nutshell, these were my discoveries:
-The theory “faster is better” has an element of truth to it – A faster projectile will be less affected by the wind and by gravity.
-The theory “faster is better” can be chucked out the window once the pellet enters the transonic zone
There are plenty of great high-powered air rifles out there, but there’s one thing that makes the Air Arms S510 a cut above the rest, and that is the adjustable power. There are some rifles out there with preset power modes, but can they be finely adjusted? Very few can. The S510 Xtra allows the user to tweak the power until he finds that sweet spot where there’s a flat trajectory and a stable projectile, and then lock it down via a small hex screw beneath the air cylinder.
That being said, there are other ways to optimize the long-range performance of your air rifle:
-A pellet with a higher Ballistic Coefficient will have a flatter trajectory and retain its terminal energy better. I have since switched to JSB Exact Heavies (10.34gr) which have a higher BC and give me better long-range performance.
-A larger caliber (.22 or .25) will allow you to shoot at a higher energy without pushing the velocity too high.
-Try out different pellet head diameters to see which one works best in your barrel. It will be different for every rifle – Mine seems to like the 4.52mm JSBs.
Experimentation is always a good thing! Since making the power adjustment I’ve been smacking pigeons, Starlings, Ground Squirrels and Hyrax from as far as 120 meters! If you don’t try new things, you may never know what secrets and techniques you’ve been missing out on – The sky is the limit!