The AirForce Condor - Part 3
Filling the gun
by B.B. Pelletier
Today, I'll discuss filling and the performance curve of the Condor. SavageSam reminded me that I promised this for Part 2, and another reader is having problems with his .177 Condor. All of these topics pertain to the same subject - how the Condor performs on a fill.
History of the Hi-Flo valve
When AirForce developed the Condor Hi-Flo valve, the greatest attention was devoted to its performance in a .22 caliber rifle. They tested the valve in .177, but they concentrated on .22 because the felt most buyers would want that caliber. That proved correct, because more than 98 percent of the Condors shipped are .22.
As more .177s were sold, however, there were some reports of rifles dumping all their air on the first shot. Some of those reports were cleared up by instructing the owners to seat their pellets deep in the barrel, but there were still a couple rifles that dumped air. The solution was to increase the firing valve return spring rate for a more positive closure. AirForce then extensively tested the modified valve in both .177 and .22 rifles, and it proved out in both calibers.
However, the fill level of the rifle with the new valve was sometimes less than 3,000 f.p.s. It wasn't true for all rifles, but a fair number of them preferred to be filled to not more than 2,800 psi, and in a few cases as little as 2,600 psi. I remember one customer in California who swore his rifle could only take 2,500 psi, but when we had him check his fill gauge against a calibrated one, he found his gauge was reading low. The fill pressure really was 2,800 psi. That case is the reason I've written several articles about the inaccuracy of small fill gauges.
Remember that an AirForce rifle butt reservoir is where the firing valve is located, so we really aren't talking about rifles. We're talking about air tanks.
When this situation arose, I did extensive testing of air tanks with maximum fill levels below 3,000 psi to determine the performance curve. It took a lot of time just finding enough air tanks to test, because there weren't that many of them, but I did locate enough for a test. What I found was that the maximum fill pressure might vary, but the total number of powerful shots remained the same. The starting and ending pressure were simply lower than what was normally the case.
A revised valve
AirForce informed their customers about the possibility of lower maximum fill levels and about the inaccuracy of small pressure gauges. But they also redesigned the valve so all of them can take a 3,000 psi fill. This new valve has been shipping for over a year, so all new guns have it.
I have a Condor with a tank that had an early valve that was red-hot. It had been loaned to a sales group for a couple years; when they returned it, I got it. It accepted a 3,000 psi fill and pushed a 14.3-grain Crosman Premier 1,270 f.p.s. on the first shot. On shot 20, it was still going 1,176 f.p.s. After AirForce upgraded my tank to the new valve, I got the same valve that most of you have. Now, the first shot's velocity is about 1,235 f.ps., and shot 20 is about 1,189 f.p.s. The performance curve did not change.
A few people will look at the difference between 1,235 f.p.s. and 1,270 f.p.s. and say the new valve is weaker! Yes, if you do the math, it does have less total velocity, but LET'S GET SERIOUS! No other air rifle in the world can do what the Condor does, so we're carping about a point that doesn't matter. Individual Condors will still go faster than mine, and some may go slower. IT DOESN'T MATTER. No sane shooter is going to shoot pellets that fast to begin with. If you want power, you load a 28-grain Eun Jin, which my rifle pushes at 1,010 f.p.s. on shot No. 1. If you want the ultimate in accuracy, you dial the power wheel down to No. 4 (on my rifle) and shoot a 15.8-grain JSB Exact at 1,030 f.p.s. Yes, I know what I say about shooting pellets faster than 900 f.p.s., but my Condor will group JSBs wonderfully at that speed.
To the guy who told me his .177 Condor dumps all it's air at 2,500 psi, I say this:
- Have you tested that pressure with a calibrated air gauge?
- Are you certain you're seating the pellets deep in the bore?
The Condor performance curve
Condors give an amazing number of full-power shots on a single fill of air. Unlike the powerful Korean rifles that decrease in velocity with every shot (the new 500cc Sumatra will probably be an exception), the Condor sustains its power for about 10 shots. Then, the next 10 shots decline so slowly that they're still useful if you're hunting small game out to 50 yards. For longer shooting, you probably want to refill after 10 shots...but let's have some perspective. Before the Condor came along, nobody ever expected to shoot more than two or three shots at great distance before refilling. It was the Condor that made it possible for the first time. We are talking about shots with greater than 60 foot-pounds at the muzzle - compared to the 55 foot-pounds and less that other rifles get.
What if I don't shoot at full power?
The Condor owner has to discover where his rifle performs best, because there are an infinite number of variables that affect performance. I could blog Condor performance curves every day for the rest of this year and someone would still be able to ask about something I hadn't done. You cannot expect to shoot an Eun Jin pellet at 65 foot-pounds on shot No. 1 and then dial down to 25 foot-pounds for shot No. 2 with a Crosman Premier. The rifle doesn't work that way. Both types of shots are possible, but you must be in the right part of the power curve (pressure left in the tank) and have the power wheel set at the right place to get the performance you desire. It's not like throwing a switch. But, since no other air rifle in the world is as flexible, it's worth the effort to find the performance you want from your rifle. That's what a chronograph is for! It's not for amusement; it's a tool to discover the performance curve you desire with a certain pellet in your rifle. You can't expect to transfer that information to someone else's rifle. He has to do the work, himself.
I can see the question now, so let me answer what you haven't yet asked. "Pressure left in the tank, you say? How can I know how much pressure is in there when AirForce hasn't put a pressure gauge on the tank?"
How to determine maximum fill pressure
You do it the same way I discovered the best max-fill pressure for my Daystate Harrier, a more expensive PCP rifle that also has no gauge. You fill to a pressure above what you believe the best operating pressure to be and start shooting pellets through the chrono. The velocity will climb, then stabilize. Fill the tank a second time and when the velocity reaches that same stable velocity, immediately refill the tank. Those who own PCPs can tell the moment their tanks begin to accept a fill. With an AirForce tank being filled from a scuba tank, the needle stops climbing rapidly and the sound changes. When filling with a hand pump, the needle stops climbing steadily and seems to rise and fall with every pump stroke. Owners have seen this countless times and know it means their tank's valve is now open and accepting a fill. The pressure at which the tank begins to accept air is the max-fill pressure for your rifle, for whatever you're trying to do.
SavageSam, I just answered your question about fill pressure. For the rest of you, this is the way PCP owners have determined exact fill pressures for their rifles. Stop filling blindly to a "number" and spend the effort to discover the real fill pressure of your rifle. This also takes care of gauges that aren't reading right.
Learn how to set up your rifle
Guess what? The max-fill for shooting Eun Jins at 1,000 f.p.s. will probably be different than the max-fill pressure for shooting JSBs at 950 f.p.s. You may get only 15-20 shots with the Eun Jins with a higher initial fill pressure than you do when shooting 40 JSBs at 950 f.p.s., using a lower initial fill pressure. Learn to set up the rifle to do what you want it to do.
Whew! I'm sweating just thinking about all of this, and I've only scratched the surface of the Condor's flexibility. For instance, I made no mention that you'll have to re-zero your rifle every time you want to shoot a different pellet at a different velocity. Do you begin to see why I preach finding one pellet and one velocity for each rifle? Changing over is the same as zeroing a new rifle. But, the Condor is the one and only rifle on the market that offers the flexibility to do nearly everything you want to do.
The Condor paradigm
Newer shooters must be overwhelmed by all this discussion of fill pressures, pellets and velocities, but here's what a Condor lets you do that no other air rifle in the world can copy. It allows you to handload your air rifle. Firearm shooters who load their own ammunition are called handloaders. They select gunpowder types and weights and bullet types and weights that produce the results they want. A shooter who doesn't handload may be able to buy only 60 different types of ammunition for his .30/30, while a handloader can easily come up with thousands! Most of those thousands are useless, but a couple dozen are real gems that aren't sold anywhere. That's the joy of handloading. Condor owners are among the very few airgunners who enjoy the same flexibility.