How fast do pellets go?
by B.B. Pelletier
This report is for Herb, who requested it several weeks ago. I'll present empirical (observed) data on this topic--not theory. I have been testing airgun velocities since the first day I got my first used chronograph in 1994, and I've learned quite a lot just by watching.
Can pellets go supersonic?
There have been several arguments over the years that, since they are driven by compressed air, pellets cannot go supersonic. Let me lay that one to rest right now. I've shot thousands of pellets faster than sound--the most recent was during the test of the Career Infinity a couple weeks back. Yes, pellets do go faster than sound.
When I first started chronographing pellets, I was curious to see if the .177 RWS 48 sidelever could drive light pellets to 1,100 f.p.s. Those were the days before trick lightweight pellets, so we relied on RWS Hobbys that were lighter than they are today. I saw many shots in the 1,050 f.p.s. region, but other than obvious detonations, I didn't see any that went 1,100 f.p.s. When you think about it, though, 1,050 f.p.s. is pretty fast.
Then came the 1250 Hurricane
The next big leap forward came when Gamo brought out the 1250 Hurricane, a breakbarrel springer they claimed could shoot 1,250 f.p.s. I was fully prepared for this gun to also shoot less than the claim, but to my surprise, it didn't! In the first test, I got a velocity of 1,257 f.p.s. with a Hobby pellet. The average speed for the string was less than that--about 1,220 f.p.s. as I recall, but the gun really did achieve its advertised speed. And it was so much faster than the speed of sound that nobody who witnessed a shot could doubt it and keep a straight face. The supersonic crack was convincing evidence, because it always came well after the sound of the discharge.
And then the AirForce Condor
Then I went to work for AirForce. For the first 18 months, nothing big happened in the supersonic realm, but then AirForce owner, John McCaslin, came out with the Condor--a rifle that exceeded 1,200 f.p.s. in .22 caliber. In fact, I test-fired each one of the first 100 guns to ensure they were going faster than 1,250 f.p.s. with Crosman Premiers. We didn't ship them unless they were because we knew there would be an army of new owners sitting out there with chronographs waiting to expose us if the guns didn't perform.
We kept a ledger of those first 100 guns, some of which exceeded 1,280 f.p.s. with .22 Premiers. They were the fastest .22 caliber air rifles the world had ever seen, though by this time I knew that certain Korean rifles like the Career 707 could sometimes get a first shot out the spout at 1,270 f.p.s. But the Korean rifles couldn't keep shooting that fast. They declined in velocity with each shot, while the Condor kept the first 20 shots faster than 1,200 f.p.s.
Believe it or not, it was nearly a complete year before anyone thought to test the Condor for the top velocity in .177 caliber. Heck--we were already over 1,200 f.p.s. in .22 with medium-weight pellets. How much faster did we need to go? However, the day finally came when AirForce wanted to know how absolutely fast the .177 could go, so I got tapped to test it. I already knew it would go over 1,300 f.p.s. with a .177 Hobby, but Skenco Hyper-Veloocity pellets were available then and they weighed over a full grain less than Hobbys, plus their bodies were plastic, not lead. Surely they would be the fastest.
And they were. I fired several 5.4-grain Skencos, and the fastest recorded shot went 1,486 f.p.s. Had I known at the time how big an issue this would become, I would have photographed the chronograph readout, but I didn't. As of today's date, 1,486 f.p.s. is still the fastest velocity I've seen from a pellet being driven by air, alone. I've seen plenty of shots powered by a fuel/air detonation that have wandered into the 1,700 f.p.s. realm, but those are shots from a firearm, by definition. When just air is the propulsive force, 1,486 f.p.s. is the best I have seen.
A year went by and then Gamo brought out their Performance Ballistic Alloy (PBA) pellet, made from a non-lead casting metal plated with 18-carat gold. The Raptor pellet was the first PBA to hit the market, and it increased the velocity of almost everything it was used in. A year later, the Hunter Extreme came to market with the claim that it could shoot a pellet over 1,600 f.p.s. Actually, the gun bears a sticker that claims 1,650 f.p.s. Gamo even showcased the gun and pellet on Jim Scoutten's Shooting USA television program, where the camera recorded the rifle shooting a Raptor through the chrono at over 1,630 f.p.s.
So, I tested a Hunter Extreme. To my surprise, however, it failed to achieve even 1,400 f.p.s. The best I saw was 1,395 f.p.s. I asked other Hunter Extreme owners to report their top velocities to me, and the best I got was a third-party report of 1,425 f.p.s. What was happening?
What happened is very clear. The rifle shown on TV was detonating! I can get the Hunter Extreme over 1,600 f.p.s. by introducing a light oil through the air transfer port. Anyone can. When the piston compresses the air, the heat of compression ignites the oil droplets, causing an explosion. But I challenge anyone to shoot the rifle for 50 shots AND THEN chronograph it! I'm pretty sure they won't see velocities above 1,400 f.ps. with PBA pellets. I don't know if I've convinced you about this or not, but I am satisfied that the Gamo Hunter Extreme is not capable of achieving 1,600 f.ps. with PBA pellets in a supervised and honest test.
Before we move on, I have two more comments. First, 1,395 f.p.s. (the fastest I have ever been able to get a Raptor to shoot in a Hunter Extreme on air, alone) is not a poor performance! It's stunning! But it's not 1,600 f.p.s. and people need to know that, so when some gun really does shoot that fast it can get credit for doing it honestly.
The second thing is that Gamo now advertises their .22 caliber Hunter Extreme as shooting 1,300 f.p.s. in .22 caliber, which they say makes it the fastest .22-caliber air rifle on the planet. That statement is untrue--plain and simple. I have shot several shots from .22-caliber Condors faster than 1,300 f.p.s. I did it years ago, before Raptor pellets existed in .22 caliber. I always tested Condors with 14.3-grain Premiers, so all it took to pass 1,300 f.p.s. (with some guns--not with all of them) was to drop down to a lighter lead pellet. It was no trick; the gun was always that fast. Who knows how fast it would be with a trick pellet?
Enter, Dennis Quackenbush
I got a call from Dennis Quackenbush late last year. He wanted to test maximum pellet velocities because of things people were saying on the Yellow Forum. He constructed a special testbed smoothbore gun in .25 caliber and .375 caliber. We tested both versions at the 2008 LASSO big bore airgun shoot in Texas, and I filmed the test. That video is provided for you in a new article on the Pyramyd Air website. That article and video is the summation of this report.
So Herb, that's my report. It's as far as I've seen pellet velocity testing go to date. These numbers have all been witnessed--sometimes by over a million viewers, so nobody can argue they aren't real.