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by Tom Gaylord
Copyright PyramydAir.com ©2009. All Rights Reserved.
At the end of this article is a video that I filmed December 2008 at the LASSO (Long-range Airgun Silhouette Shooters Organization) shoot outside of Dallas, TX.
This subject is confusing for new airgunners because many modern air rifles and a few air pistols are advertised to have velocities they cannot achieve. I've been testing this phenomenon for many years--ever since Gamo brought their 1250 Hurricane to market. That rifle was advertised as achieving 1,250 f.p.s., and the .177-caliber rifle I tested actually reached 1,257 f.p.s. when shooting RWS Hobby pellets.
The early years
My early tests were conducted in the days before the Gamo Raptor PBA pellet and other non-lead lightweight pellets were available. At that time, all I had available were lightweight lead pellets and the RWS Hobby was the lightest of them.
When the lightweight pellets did come out, nobody said much about what they did for airgun velocity until Gamo started their campaign with their Performance Ballistic Alloy, or PBA. The Raptor pellet is made from PBA , which is some non-ferrous metal that casts well--probably a zinc alloy--and is plated with 18-carat gold. A .177 Raptor weighs 5.4 grains, so the lighter weight adds considerable velocity to a rifle over standard lead pellets that start at about 7 grains.
Gamo has incorporated this fact into their advertising and now lists the velocity of some of their air rifles with two different speeds--one for PBA and a second number for lead pellets. And that ad campaign was what started my investigation into pellet speeds.
I haven't seen it yet
I've never witnessed a pellet going as fast as Gamo (and now Benjamin) advertises. Gamo advertises their .177-caliber Hunter Extreme at 1,600 f.p.s. when shooting PBA ammo. Benjamin advertises the Super Streak at 1,500 f.p.s. Benjamin doesn't mention a specific pellet, but since they manufactured the now-discontinued Silver Eagle hollowpoint that weighs only 4.8 grains and in my testing had always beat the Gamo PBA for speed, I assume they meant the Super Streak to shoot that.
The airgun forums are alive with talk of pellet velocities. Some say it's impossible for a pellet driven by air to exceed the speed of sound, which is around 1,100 f.p.s., at sea level. Others argue that speeds of well over 1,600 f.p.s. are very possible.
Before we go any farther, let me explain that it is entirely possible to trick an air rifle into shooting a pellet over 1,600 f.p.s. Introducing a flammable liquid, such as oil, into the gun's compression chamber will cause it to detonate, driving the pellet well past 1,600 f.p.s. But that would be the result of a chemical explosion, making the gun a firearm, not an airgun. Daisy made a .22 caliber round that had solid fuel bonded to the base of a bullet, and it was ignited by a spring-piston airgun mechanism. But that was a firearm and subject to all regulations governing firearms.
We're talking about airguns, not firearms. For that reason, we must rule out guns that use chemical explosions to achieve their velocity. That eliminates the Gamo Hunter Extreme and the Benjamin Super Streak. In tests I have conducted the fastest a Gamo Hunter Extreme was able to shoot with .177 PBA pellets was 1,395 f.p.s. The fastest the Benjamin Super Streak went was 1,323 f.p.s., again with PBA pellets.
The fastest I've seen
However, I have witnessed faster pellets. When I worked at AirForce Airguns, I had occasion to test all manner of guns and pellets, and one time I saw a 5.7-grain .177 caliber Skenco Hyper-Velocity Lead-Free pellet go through the traps at 1,486 f.p.s. That's the fastest pellet I've seen to date that didn't involve an explosion.
Dennis Quackenbush and I have been discussing this issue for a long time, and in 2008 he decided to do more then just talk. He built a special smoothbore version of his Outlaw rifle and barreled it in both .25 caliber and .375 caliber. He made two smoothbore barrels for the gun--one in either caliber--and produced lightweight "pellets" made from Delrin, an engineering plastic. He shot his test gun through my Oehler chronograph at the 2008 LASSO big bore shoot, and I filmed the whole thing for this article.
The video tells the whole story, unfortunately the portion where the .25 caliber pellet was filmed was lost. However, the maximum speed for the .25 caliber, 7-grain Delrin pellet was 1,425 f.p.s.
The bottom line
You'll see in the video that the modified rifle owned by Big Bore Bob Dean shot a 15.5-grain Delrin pellet at 1,474 f.p.s. That's the fastest shot I have on record. I won't say that faster pellets are impossible, but so far my experience indicates that they don't happen.
Now, watch the video!