Precharged pneumatics, regulators and power adjusters: Part 1
by Tom Gaylord
Writing as B.B. Pelletier
This report covers:
- Two things
- What is an air regulator and what does it do?
- How does the valve behave?
- So — why have regulators?
- Why you need a chronograph
- What I have not yet addressed
Today’s blog was a gift from reader Michael, with several others joining the discussion. Here’s what Michael said last Thursday.
I’m not a future TexanSS owner, but I enjoy reading about any model of AirForce air gun. I have considered buying a TalonSS ever since AirForce came out with them, and I’ll keep thinking about one until I someday break down and get one.
They are accurate, lightweight, cool looking, etc., but to me the greatest appeal is AirForce’s wide ranging power adjustment. To me that is huge. Want to increase shots-per-fill for target practice? Dial it down. Want to rid your side yard of that pesky squirrel but you have a .25 Condor? Dial it down to squirrel power.
But too many of the PCPs hitting the market these days lack an easy to use power adjuster. Why is that? Is it difficult to implement in a design? An expensive-to-provide feature?
My answer was as follows.
Wow! What a question!
“But too many of the PCPs hitting the market these days lack an easy to use power adjuster. Why is that? Is it difficult to implement in a design? An expensive-to-provide feature?”
And then he added:
The Marauder is a hybrid that is adjustable, but it requires tools and monkeying around. Cometa, Evanix, Kral and roughly one third of Air Arms’ models offer power adjusters. Who does not? Hatsan, Ataman, Diana, Weihrauch, Benjamin, Beeman, Umarex, Crosman, BSA, Gamo, Career/Sumatra/Air Venturi, Walther, and Hammerli.
Once he got wound up he couldn’t stop commenting.
Ever go into a “hipsterish” coffee bar wanting a simple cup of black coffee, only to see a menu board with 23 different coffee varieties with 14 different methods of preparation with four kinds of milk and 31 different flavors of syrup? If you’re like me, you stumble out of the place with no coffee but the beginnings of a tension headache instead. When it comes to power adjusting the Marauder is a hipster coffee bar.
Does it have marked power settings and a knob or lever to select them? If my memory of the Marauder is correct, adjusting the power requires using an Allen wrench (maybe two Allen wrenches of different sizes) to adjust two different aspects of the hammer, each of which affects the operation of the other. Then the shooter must use a chrony to determine if the power change is what he wishes or not. If not, Allen wrench in hand, he goes back to adjusting the hammer in two different but interrelated ways. Then back to the chronograph.
I beg you not to be offended, but you have written at great length and in fine, expert detail in past reports on the labyrinthine processes of adjusting the Marauder’s hammer and the effects each quarter turn has on velocity and on the other hammer adjustment’s quarter turns. Marauders are a tinkerer’s dream. But not everyone desires to adjust, chrony, adjust, chrony, adjust, chrony, and so on just to go out and plink for a half hour or go out and eradicate one squirrel.
Some airgunners just want a cup of black coffee. “Strong, medium, or mild, Sir?” That is manageable.
With AirForce, Air Arms (the adjustable models), Cometa, and so on, select one of the marked power levels (no tool required) shoot once to complete the two-step process, and Voila!
Before I could catch my breath, reader Halfstep chimed in.
I can give some examples that I own that don’t have any power adjustments at all. The Wildfire and Stormrider aren’t adjustable and I assume that it’s because it would add a lot of cost to such a low cost gun. Neither the Gamo Coyote or Urban are adjustable either. They are both tuned so well from the factory that their power curve almost looks regulated. I think they or maybe the manufacturer, BSA, even refers to it as a self-regulating valve. A user adjustment might throw that out of wack.
You said there would be more description to come so I don’t want to jump the gun, so to speak, but is the Texan SS regulated and if it is, is that adjustable?
And just when I thought the onslaught was finished, reader Vana was heard.
You talking about me??? 🙂
Would love to see a detailed blog on regulated vs. non-regulated rifles.
A comparison of a standard Maximus before and after an after market regulator installed would be extremely interesting. (GunFun1 and Chris USA have done this mode )
And then more from Michael.
More PCPs with fixed power: Daystate, Kalibr, FAS.
FX has three powers settings.
I knew I had a blog now! But the comments kept coming. Reader GunFun1 tried his had an answering Michael.
Think about this also with the power adjustment. Yep it’s easy to dial the power down for the pest bird in the yard and up more for the squirrel out at 60 yards.
But here’s what to think about. What happens to POI/point of impact when the power is changed? It goes up or down. So that means now you have a gun whose shifting impacts at different power settings need to be learned.
I use to do that with my first Talon SS and Marauder. But I found out after time that it’s best to tune the gun for what velocity and fill pressure you want and leave it alone. In other words don’t keep changing the gun settings for a paticular time of shooting.You get a much more consistent gun that way by leaving it set at that particular setting. And what I mean by that is a accurate gun and a accurate person shooting that gun. When your pesting or hunting you need to know where that pellets going to hit in relation to where you aim. Sometimes it’s hard enough learning the holdover or under at one setting let alone multiple power settings.
That was just the introduction to today’s report! Let’s get started.
I will boil today’s discussion down to just two things — What is an air regulator and what does it do?, and How does the valve behave? In the next installment I will cover power adjusters, but you need to understand valves and regulators first. I’ll start with the regulator.
What is an air regulator and what does it do?
An air regulator is a gateway between high pressure air and working pressure air. In a scuba tank a regulator makes it possible for people to breathe under water by reducing air pressure inside the scuba tank from thousands of pounds per square inch to air at a pressure a person can breathe. In a precharged airgun a regulator reduces air to a pressure that is ideal for the firing valve. The goal is that there is enough air for each shot without wasting any.
Okay, hold that thought in your mind as I talk about a firing valve.
How does the valve behave?
Air valves in airguns allow air to pass from the reservoir to the barrel, where they push the pellet out. Some valves, like the ones in the powerful guns from Korea, are not well-balanced — or at least I have never seen any that were. They start out at the highest velocity and drop in a straight line as the pressure in the reservoir decreases. If the gun has two power levels you can shoot it on low power and get a range of velocities that rises to a peak and then drops back off as described. There is no place where such a gun will shoot shot after shot at nearly the same velocity.
Other airgun valves have a very broad range of shots with the pellet going close to the same velocity. The best one I can think of is the USFT, designed and made by Tim McMurray. It’s a gun that gives 55 shots within 20 f.p.s. and that’s a 10.65-grain H&N Baracuda Match traveling over 900 f.p.s. I had a test target with mine in which 25 shots were in a hole measuring 0.663-inches between centers at 51 yards.
The USFT gets a large number of shots at similar velocity without a regulator.
Neither airgun I just described has a regulator. And THAT, dear readers, is the most important thing you can learn from this report. You don’t need a regulator to have many shots at consistent velocity.
So — why have regulators?
Here comes the next lesson. Only the USFT valve is balanced well enough to give the kind of performance I just described. It does so on a fill of 1,600 psi inside an enormous reservoir. That valve doesn’t just get built and installed. No, it’s far more than just production and assembly! That valve has to be hand-tuned and adjusted to deliver the kind of performance it does. Think regulators are expensive? So are valves that take hours of fiddling and testing to make them work that well! Either way, you are paying for something.
Now I will bring it all together. A certain company makes a PCP with a well-regulated firing valve. It gets 26 shots that are within 20 f.p.s. of each other. But, if they could supply the SAME air pressure shot-after-shot, the same valve would keep all its shots within 7 f.p.s. And, if they could fill the reservoir to a higher pressure (which is the same thing as building a larger reservoir to hold a greater volume of air compressed to a lower pressure) and still supply air at the same pressure the valve liked, shot-after-shot, their gun would then get 31 shots whose velocity does not vary more than 7 f.p.s.
Would that gun become more accurate? No! Not unless the velocity at which it is now firing also happens to be the most ideal velocity for that particular airgun and pellet combination! If you are willing to spend a few hundred dollars extra, and if the company is willing to offer the service, then have them hand-tune your gun to shoot at the exact velocity at which both the rifle and the best pellet are also the most accurate. Then, you get all the accuracy THAT AIRGUN is capable of! If you aren’t willing to spend the money, or if the company isn’t willing to offer that service (and most of them aren’t), then the only one who can adjust it that well is YOU!
And THAT, Michael, is why the Benjamin Marauder is worth thinking about. It’s also why an AirForce Talon SS is a great airgun within its limits. But don’t expect it to do as well at the lowest power as it does at medium to medium-high power. And finally — BUY A CHRONOGRAPH! It is the only way you will ever know the things I am talking about with certainty.
Why you need a chronograph
In this report I hope you have seen that there is no magic velocity to look for. Each airgun will be different and will need the right pellet at the right velocity to give its best performance. Some guns are very forgiving and are accurate with many pellets at many different velocities. Other airguns are very picky about the pellet and velocity they prefer. When you have a chronograph you gain insight into the hidden data that may be the hinge on which your airgun’s success rides.
What I have not yet addressed
I have said very little about power adjusters in today’s report. Yet this is a report about power adjusters, as well as regulators. That discussion is still to come.
My goal for this report is to give you information that helps you understand what air regulators can and cannot do and what affect a power adjuster will have on an airgun. We got partway there today, but there is more to come.