Why do you need a chronograph?

by B.B. Pelletier

Okay, the bottom line is, you don’t need a chronograph. If all you do is shoot, you never need to use a chronograph for anything. But, if you want to get the optimum performance from your airgun and if you want to diagnose the health of your airgun, a chronograph is an essential piece of equipment.

Imagine a doctor without a stethoscope. He’s still a doctor and he can still do lots of things; but a major tool has been taken away, and there’s no way he can get around not having it. That’s you without a chronograph. Allow me to explain.

Let’s say that you want to get into the world of precharged airguns, and let’s say you’ve read enough to understand that you don’t just fill them to their maximum fill pressure and start shooting. Oh, you can do that, and it’ll work, but you’ll never know how well it works unless you can diagnose how the gun performs. Let me illustrate with a story.

Years ago, I bought an Air Arms Shamal precharged rifle for a great price. It was a beautiful rifle in .22 caliber and I was anxious to get started, so I filled it to 3,000 psi and began shooting. Fortunately, I owned a chronograph that I was using to test the gun. The first shots were in the low 500 f.p.s. range, when I had expected .22-caliber Crosman Premiers to go at least 800 f.p.s. I kept right on shooting that rifle, and after about 60 shots it finally climbed up to the 800 f.p.s. level. Because of the chronograph, I discovered that the maximum fill for that rifle was only 2,600 psi. I still got about 40 powerful shots, but they happened at a different range on the pressure scale.

Years later when I the technical director at AirForce Airguns, I used to get calls from new Condor owners who were having problems with their guns. They were shooting very slowly when filled to 3,000 psi. I convinced some of these people to try lower maximum fill pressures until the first shots were powerful, but this could all have been solved if they had simply used their chronographs to determine the same thing. Sometimes, the disparity was due to pressure gauges that weren’t in agreement, but other times the rifles themselves were simply not performing well at 3,000 psi. Drop them back to 2,800 or 2,700 psi, and they work fine and still get just as many shots that were just as powerful as every other Condor.

I actually had several people tell me that because AirForce was a manufacturer they should control the maximum fill pressure of their guns better than that. I countered with the fact that they were losing nothing by their guns operating at a lower pressure level, but they weren’t satisfied. They said the company advertised a fill pressure of 3,000 psi and that is what it should be. Since I helped build and test those guns, I knew they operated in a range of fill pressures depending on dozens of variables, but that wasn’t good enough for these guys.

A correlation would be someone who buys a new car and then gets mad because it won’t go as fast as the speedometer indicates at the top end. Almost every car is like that, but nobody ever goes that fast, so nobody notices.

Then there are the folks who think that if a multi-pump is powerful on just 10 pumps, it should crack like a .22 on 20. You absolutely cannot convince them that their guns are shooting slower when they exceed the maximum number of pumps — just like a Corvette goes no faster if you try to put an extra 30 gallons of gas in the tank. In this situation, a chronograph is a de-liar. Just like a fish scale or a ruler, a chronograph tells the story the way it really is instead of what your dreams project.

A chronograph can also tell you when that old multi-pump no longer performs to spec like it once did. Maybe the pump head needs to be adjusted or maybe it just needs to be oiled — the chronograph tells that story.

A chronograph can instantly tell you the health of your single-stroke pneumatic. In fact, it’s the only way we have of knowing what the health really is. I use a chronograph when I oil the gun to see the before and after comparison.

…a chronograph is a de-liar. Just like a fish scale or a ruler, a chronograph tells the story the way it really is

CO2 guns
Oh, yeah, that new shoot-em-upski is a real powerhouse at 490 f.p.s. But, when you pull the trigger as fast as you can, shot 5 comes out the spout at 376 f.p.s. The only way you will every know that is with a chronograph. Or, how many shots do you get with a fresh CO2 cartridge? Or, how does the cold weather affect velocity? Or, how does that new tuned valve compare with what the factory sent? And any of a dozen other interesting vital statistics about your gas gun are waiting inside your chronograph.

Spring guns
How can you own a springer and not have a chronograph? Sure, the manufacturer says it shoots 1,000 f.p.s., but you really want to know what it does when shooting that one best pellet — the one that hits what you shoot at. Finding out you are shooting 789 f.p.s. with your best pellet allows you to make all sorts of adjustments to taylor the performance of the rifle to the real world.

Or, what happens when you oil the gun? Only the chronograph will tell you the truth.

How will you know when you have broken a mainspring? Diana rifles just get smoother and lighter to cock when their springs break. Unless you know the velocity, you’ll never have a clue what the gun’s doing.

What about that tuneup you just did? What did it do for you? Without a chronograph, you’re just relying on your senses, and they can fool you every time. Let me tell you another story.

Back when I was testing the Beeman R1 for my R1 Homebrew series in The Airgun Letter, which turned out to be the foundation of my R1 book, I chanced to install a Venom Mag 80 Laza Glide kit. The cocking effort jumped up to 50 lbs., but when the rifle fired it was so smooth and quiet you would have sworn it was only producing 15 foot-pounds of energy. It took a chronograph to prove that it was actually up to 23 foot-pounds.

Sure, you can shoot into boards and duct seal and all kinds of other mediums, and you’ll get relative comparisons. To put an absolute number on those speeding pellets, you need a chronograph.

They’re not expensive
Yes, I know, spending $100 for something that isn’t an actual airgun is hard to do. It’s hard for me, too. I also know there are those who are living at the edge of their finances and just cannot afford anything beyond that next tin of pellets. So, I’m not talking to them right now. But for the rest of you who, over the course of a year, spend $300 and more on your airgunning hobby, you do have the resources to own a chronograph. You just don’t have your priorities aligned correctly, because you don’t see the need. That’s what today’s report is all about…to show you the need to own the most helpful piece of equipment you can imagine for airgunning.

Heck, back in the 1960s, when I was reading all the giants of gun writing, those veterans were struggling with paper start/stop screens that had wires embedded in them and readouts on nixie tubes that had to be translated through tables to obtain velocities. Today, we have skyscreens that require no maintenance beyond awareness of where they are in relation to the muzzle, and our readouts are not only direct, they also store strings and perform useful statistics on them. Shooters who can’t calculate the mean for a string of numbers can print out the standard deviation of every string they shoot with the push of a button.

All this comes at a price, and the price has never been lower. For about a C-note, you’re in the game with a Shooting Chrony Alpha chronograph that elevates you to the same level as puffed-up writers like me. I use the heck out of my Alpha model. Even though I own an Oehler 35P chronograph that’s well-respected as a scientific instrument, my little Shooting Chrony is handier and faster to set up and use. It gives me numbers just like the Oehler does, and it does all the simple statistics I need. And, thanks to the generosity of readers of this blog, I also have the optional Shooting Chrony Ballistic Printer for when the strings get really large and cumbersome.

When should you buy a chronograph?
This is the question each of us has to answer. The answer will be different for each person, but here’s what happened to me. I’d been an airgunner for 40 years before I bought my first chronograph. In my defense, most of those 40 years were the bad years for chronographs. Only in the last 5 to 8 years did the prices drop to affordability, mainly because the Shooting Chrony came on the market.

Then, I started writing The Airgun Letter, and my need for a chronograph increased exponentially. When I started the R1 Homebrew series, the dam finally burst. How could I test the gun without one? So, at the 1993 Winston-Salem airgun show I bought a used Shooting Chrony from Paul Watts for $45. It worked fine and got me started with the R1 series, but that old model had cardboard skyscreen portals that were chewed up when I got the unit and I began chewing them up even faster. Before several months had passed, I started getting spurious readings that were 150 f.p.s. off what I knew they should be. I tracked that to the floppy, shot-up skyscreen portals and to not holding the barrel of the rifle perpendicular to the skyscreens. Edith and I freaked out, because here I was telling the world about my test gun and suddenly I felt I couldn’t trust my test instrument.

So, we popped for the Oehler 35P chronograph that every gun writer worth his salt uses. In those days (mid-1990s), you couldn’t publish gun velocities in a newsstand magazine unless they had been obtained with an Oehler of some kind. I still have that Oehler, and I use it a lot, but I use my modern Alpha Chrony even more for the reasons I’ve already mentioned. However, I’m glad I bought the Oehler when I did, because they’re no longer available new. The used prices are on the increase. Fortunately, I know of a brand-new in-the-box 35P that I would buy in an instant, should the need ever arise. It might cost me $700, but at this point my career depends on chronographs so much that I would bite that bullet without a second thought.

I would still continue to use the Alpha Chrony, as I am advising you to do. Yes, the Oehler gives more precision and yes, it has a second circuit built in, so you get not one but two different readings with every shot. Here’s the difference between this top-of-the line chronograph and a Shooting Chrony. The Oehler may say a shot went 987 f.p.s., while the Shooting Chrony may say the same shot went 996 f.p.s. The Oehler, with its 4-megahertz clock speed is 40 times more precise than the Chrony with its 100-kilohertz clock, but the actual difference on the readout is what…7 f.p.s.? Here’s the kicker — neither number is exactly correct. The Oehler is just a little “more correcter” than the Chrony. Who cares? We’re talking 7 feet per second over a range of almost 1,000 feet per second. It’s like dandruff on a white coat — nobody will notice. Besides, if all you publish is the Chrony number, then that’s the velocity. Get it? Think about that for a moment.

I know this report sounds a little like a rant and a lot like a sales pitch, and perhaps both of those are true. But, I read every week about shooters who haven’t got a clue what their guns are doing and I hurt, knowing they’re so close to ultimate awareness. For the price of a cheap springer, you can have the wool pulled off your eyes and join the growing number of shooters who cannot be fooled. Last story before I close.

Over the years, I’ve watched tadpole airgunners develop into fresh young frogs with minds of their own. The young tadpoles start out swimming around aimlessly, not knowing what’s out there or understanding the difference between a harsh spring rifle and a smooth-shooting PCP. Then, as they read, discuss and learn, their legs begin to develop and they start transforming into the dark green amphibians I know they’ll become. Finally, they pop for a chronograph, and the transformation is complete.

I read every week about shooters who haven’t got a clue what their guns are doing

Within a month, they start trying to email me spreadsheets of numbers they’ve obtained with their new toy. The last vestige of their now-useless tail has withered and dropped off, and they’ve become what destiny ordained.

Three years later, they’re fat bullfrogs with their own lily pads and dozens of airguns, a well-worn chronograph and a deep croaking attitude about airguns that can be heard across the internet. Can’t nobody pull the wool over their eyes no more — no sir! That’s when they cease being newbies and become colleagues.

Please think about it.

In August 2006, I wrote an article about the Shooting Chrony and why you’d need a chronograph. Please read it and watch the video at the end. The information there is different than today’s report, and it’s a good augmentation.