How to Build a DOPE Chart for an Air Rifle (With a Worked Example)

Ask a good long-range shooter how they hit a target at an odd distance on the first try and they will tell you about their DOPE. It stands for Data On Previous Engagements, and stripped of the jargon it just means a record of where your rifle actually hits at each distance. Build it once, keep it with the rifle, and you stop guessing at holdover. You look up the number and take the shot.

Here is why this matters more for airgun shooters than almost anyone tells them: the pellet arc is steep. A centerfire rifle shoots flat enough that holdover barely changes across close range, so a centerfire shooter can get away with a rough sense of drop out to a couple of hundred yards. A pellet does not give you that grace. It drops fast and keeps dropping faster, so the difference between a 30-yard shot and a 50-yard shot is large, and by 100 yards you are holding a serious amount of elevation. That steepness is exactly why DOPE is more valuable in airgun than in centerfire, and why the shooters who keep a good chart hit targets the rest miss.

This guide covers what to record, the two ways to build a chart, the common mistakes, and a full worked example so you can see the process end to end.

What DOPE actually is, and what to record

Your DOPE is a small table. Each row is a distance, and against it you record how much to hold over or dial up to hit dead center at that distance. That is the core of it. The value is in the details you record alongside, because they are what let you trust the chart later.

Record at least these:

• Distance. The range for that row, in the increments you shoot, often every 5 or 10 yards for airgun because the drop changes so quickly.
• Holdover or come-up. The elevation correction at that distance, expressed in your scope’s units. For a mil reticle that is a number of mils; if you dial, it is the same value on the turret. This is the number you actually use.
• Point of impact. Where the pellet landed relative to your aim while you were building the chart, so you can see the raw drop before it became a hold.
• Pellet. The exact pellet and weight. A different pellet is a different chart.
• Velocity. Your measured muzzle velocity. This is the anchor number, and it is why a chronograph is the tool the whole chart is built on.
• Temperature. Because a PCP’s velocity shifts with temperature, a note of the conditions tells you whether a later miss is the chart or the weather.
• Wind, if it mattered. Not part of the drop itself, but worth noting so you know what the day was like.

A chart with distance and holdover but no pellet or velocity is half a chart. The context is what makes it dependable.

The anchor tool: velocity first

Everything in a DOPE chart traces back to how fast the pellet leaves the barrel, so the first tool you need is a chronograph. It gives you your true muzzle velocity, which is the input a ballistic calculator needs, and it tells you your rifle’s consistent shot band so you build DOPE only across the fills where velocity is stable. Trying to build a chart without measured velocity means feeding a guess into every calculation, and the packaging number on the rifle or pellet tin is a guess. Measure it. If you have not set up a chronograph before, we cover the how and the why in how to chronograph an air rifle, and a compact radar unit makes it painless.

Two ways to build the chart

There is a hard way and a fast way. The fast way still ends with the hard way’s final step, so do not skip it.

The hard way: shoot every distance

The purest method is to shoot your way to the data. Zero the rifle, then set targets at each distance you care about, 25, 30, 40, 50, 60, 75, 100 yards, and shoot a group at each with a center hold. Measure how far below your aim the group’s center landed, convert that drop into your scope’s units, and write it down. Do it in low wind, off a solid rest, within your rifle’s consistent fill band, and shoot enough at each distance that one flier does not fool you.

This method is slow and eats pellets and range time, but it has one great virtue: it is your rifle’s truth. There is no model to be wrong, because you are recording what actually happened. Many excellent airgun shooters build their whole chart this way and trust it completely.

The fast way: chronograph, calculate, then verify

The efficient method uses a ballistic calculator to do most of the work, then confirms it on paper. Feed the calculator your measured muzzle velocity, the pellet’s ballistic coefficient and weight, your sight height above the bore, and your zero distance. It predicts a full trajectory in seconds, giving you a holdover for every range. That predicted chart is usually very close, and it saves you shooting your way blindly to each number.

Then comes the step you cannot skip: verify. Take the predicted holds to the range and shoot them at each distance. Where the pellet hits center, the prediction was right. Where it hits high or low, correct the chart to match reality. Real barrels, real pellets, and real air never match the model exactly, so the calculator gets you 90 percent of the way and the target supplies the last 10 percent. Skip the verification and you have a nicely formatted guess.

A worked example: FX Impact M4, .25 JSB King at 900 fps

Let me walk the fast method through with a common setup so the process is concrete. Say you shoot an FX Impact M4 in .25 caliber with JSB Exact King pellets at 25.4 grains, and your chronograph shows a steady muzzle velocity of 900 fps across your good fill band, with a healthy single-digit SD. Your scope sits about 1.75 inches above the bore, and you zero at 30 yards.

You feed a ballistic calculator those inputs: 900 fps, the JSB King’s ballistic coefficient (roughly 0.047 on the G1 model, worth confirming for your batch), 25.4 grains, 1.75-inch sight height, 30-yard zero. It returns a predicted trajectory. Converted to mil holds, it looks about like this:

Distance	Predicted drop	Holdover (MIL)
25 yd	+0.3 in (just above zero)	0.0 (hold center)
30 yd	0 (zero)	0.0
40 yd	-1.8 in	1.25
50 yd	-4.8 in	2.7
60 yd	-8.9 in	4.1
75 yd	-17 in	6.3
100 yd	-34 in	9.4

These figures are illustrative. Your own rifle, pellet, lot of pellets, scope height, and conditions will differ, so treat this table as a worked demonstration of the method, not numbers to copy. Build your real chart from your own chronographed velocity and your own verified downrange impacts.

A quick word on the math, because it is worth understanding rather than trusting blindly. One mil equals 3.6 inches at 100 yards, and it scales with distance, so at 50 yards one mil is 1.8 inches and at 75 yards it is 2.7 inches. That is why a 4.8-inch drop at 50 yards works out to 2.7 mils (4.8 divided by 1.8), and a 17-inch drop at 75 yards is 6.3 mils (17 divided by 2.7). The drop in inches grows fast because the pellet is slowing and falling the whole way, which is the steep airgun arc in numbers: from under 2 inches at 40 yards to nearly 3 feet at 100.

Now you verify. You take that chart to the range on a calm day, hold 2.7 mils at 50 yards, and shoot. If the group centers, that row is confirmed. If it prints a touch low, maybe your real velocity or BC differs slightly from the model, you nudge the hold to 2.9 mils and note it. You walk each distance the same way, correcting where reality disagrees with the prediction, until every row is confirmed by actual impacts. That corrected table, with the pellet, the 900 fps velocity, and the day’s temperature written at the top, is your DOPE.

Note how much the holds change across short range: from zero at 30 yards to 2.7 mils at 50 to 6.3 mils at 75. A centerfire shooter almost never deals with that much elevation change inside 75 yards. This is the whole reason airgun DOPE matters, and why a holdover reticle earns its keep.

A note on ballistic coefficient, drag models, and apps

The one input people get wrong in the calculator is the ballistic coefficient, so it is worth understanding. A pellet’s BC is low, and it is not perfectly constant, because the diabolo shape sheds speed differently than a bullet does. Most ballistic calculators default to the G1 drag model, which was derived from a flat-based bullet profile that looks nothing like a wasp-waisted pellet. So a single G1 number for a pellet is an approximation, and it tends to drift at distance where the shape difference matters most.

The practical consequence is simple: expect to tune the modeled BC until the predicted drops match your verified impacts. If the calculator says 2.7 mils at 50 yards but the pellet consistently needs 2.9, you nudge the BC down a hair until the model agrees with the target, and now it will predict the untested ranges more accurately too. You are calibrating the model to your pellet and barrel, which is another reason verification is not optional. A few airgun-aware tools make this easier: Strelok Pro is the common phone choice and lets you fit a curve to observed drops, Hawke’s ballistic calculator pairs with their reticles, and the long-standing ChairGun tool was built for airguns specifically. Whichever you use, feed it your chronographed velocity, not the box number, and let your real impacts have the final say.

A word on wind, since your DOPE rows can note it. Wind does not change your drop, but it pushes the pellet sideways, and a light pellet moving at airgun speeds drifts more than newcomers expect. Recording the wind on the day you built a row helps you separate a genuine elevation correction from a windy-day flier, and over time you build a feel for how much your pellet moves in a given breeze. That windage sense is its own kind of DOPE, gathered the same way: shoot, observe, record.

Common mistakes

A few errors quietly ruin otherwise careful DOPE.

Using the manufacturer’s velocity instead of your measured number. The box velocity is optimistic and generic. Your barrel produces your speed, and even 30 fps of difference moves your holds at distance. Always build from a chronographed number.

Ignoring temperature. A PCP’s velocity drifts with temperature, so DOPE built on a warm afternoon can be off on a cold morning. Note the temperature you built it at and re-check when the season swings.

Building across the wrong fill band. If you gather drop data while your rifle’s velocity is climbing or falling across the fill, your holds will be inconsistent because your velocity was. Run the fill test first, find your stable shot band, and build DOPE only inside it.

Skipping verification. The calculator is a prediction, not the truth. Confirm every hold against real impacts before you trust it on a live target.

Not writing down the pellet. Change pellets and the whole chart changes. A DOPE sheet that does not name the pellet and weight it was built for is a trap waiting to spring.

Putting it to use

DOPE is only useful if you can apply it quickly, and that comes down to your optic and your zero. A first focal plane scope with a clear holdover reticle lets you use mil holds at any magnification, which is why it suits airgun shooting, and a proper zero is the foundation the whole chart sits on. If either of those is not squared away, the best DOPE in the world will not save the shot.

So build your chart on measured velocity, verify it on paper, keep it with the rifle, and update it when the pellet, tune, or temperature changes. The chronograph is the tool that supplies that anchor number, and if you do not own one yet, the compact radar unit below is where I would start.

To go deeper on the pieces around it, read how to chronograph an air rifle for the how and why, our best air rifle scopes guide for the holdover glass that makes DOPE usable, and how to zero an air rifle scope to set the foundation it all rests on. Some links on this page are affiliate links; see our full disclosure.