One number changes every wind call. Gun Number.
A wind call you can make in two seconds, without a Kestrel, without a cheat sheet, without math you have to think about. Refined by sniper sections in Iraq and Afghanistan so a warhead could land on a forehead in the time it used to take to dial a solver.
That's it. Your gun number is the single mph value where wind hold matches the range constant. Find it once. Use it everywhere.
- Published
- March 25, 2026
- Runtime
- 21:48
- Views
- 32,873
- Instructor
- Steve Holland
What "Gun Number" Actually Means
Your gun number is the wind speed, in miles per hour, where your bullet's pure wind drift — measured in mils — matches your distance to target written in tenths. At 100 yards you hold 0.1 mil. At 600 yards, 0.6. At a full thousand, a full mil. Find the single mph value that lines up cleanest across those closer ranges, and that number belongs to you and your rifle.
Where the formula came from 0:00
The quick-wind formula came out of Iraq and Afghanistan. Sniper sections were running the same ammunition and the same gun on purpose, which let them pool experience and refine a wind call they could shout across a position and apply in seconds. Not something that required pulling a Kestrel, dialing a solver, and reading off a card while a target was actively trying to leave the area.
The same teams that built it also ran mixed calibers — .300 Win Mag, .308 in a gas gun, .308 in a bolt gun, 6.5 — and the mil hold for the same wind looked different on every rifle. Gun number is what bridged that. Each shooter knows his own number. The spotter calls wind in mph. Everyone holds correctly without anyone trying to translate mils across the line.
Why it exists at all
Calling wind down to the mile per hour is the single biggest separator between top-tier competitors and everyone else. Guys at that level are putting down 10,000+ rounds a year — that's the cost of admission to that kind of intuition. Most shooters starting out should be working in a 5–6 mph bracket; the call tightens to 4, then 3, then 2, then 1 over time and reps. Pretending you're already at 1 mph is how hits become misses.
Gun number doesn't ask you to be elite-tier good. It asks you to know one number cold, then call the actual wind as a multiple or a fraction of it — full, half, quarter, double, triple. That's a problem most shooters can actually solve from the prone.
The payoff
For a 6.5 Creedmoor at sea level, your gun number is six. In 6 mph of full-value wind, on a standard man-size target, your hold is the rifle's natural drift — and that's minute of man: at or under your gun number, the wind drift stays inside a man-size target, so you aim dead center instead of making a call at all. You don't dial. You don't hold off. You break the shot.
A .223 sits around two. A .308 lands at four. A 7 SAUM pushes all the way out to twelve. The bigger your number, the wider the wind window where the rifle does the work for you and the call gets simpler.
Three steps with your range card
Build the range card
Pull dope at 100-yard increments out to your max distance. Use the wind-drift column only — not total drift. Total drift adds spin drift into the number, which doesn't belong in this math. If your app only shows total, toggle spin drift off (or set Coriolis and spin to zero) so the column reads pure wind.
Start at the right bracket
Don't scroll blind. Seed it by caliber: a .223 starts around 1, 2, 3 mph; a .308 around 3, 4, 5; a 6.5 around 5, 6, 7. Write those three columns down, then find where the tenths line up — 100 yd ≈ 0.1 mil, 200 yd ≈ 0.2, 300 yd ≈ 0.3. The mph column that matches cleanest at the closer ranges is your gun number, because that's where the quick call gets used.
Lock it to memory
Gun number lives in your head. If you have to reference a cheat sheet, you aren't using gun number — you're using something else. The cheat sheet has its place. It's just not the same tool.
This is a 6.5 walked across three candidate columns. Read down each mph column and find the one where the holds track the tenths: 100 yd at 0.1, 200 at 0.2, 300 at 0.3. Here that's the 6 mph column — so this rifle is a 6 mph gun. Illustrative drift figures, not real dope; pull your own card from your own load.
Typical Gun Numbers by Cartridge
A starting point — not a final answer. Your specific load, barrel, and atmospherics will push you a click either way. Use this to know where to start looking. And look at that 7 SAUM: wouldn't it be wild to not even make a wind call into 12 mph? There are guns out there that are exactly like that.
Run the Math Live
Set your gun number, dial a target, call the wind. The calculator walks the formula and rounds up — "go bold on your wind" — to the nearest tenth of a mil.
Two rounding steps: round your range up first (566 yd becomes 600, so 0.6), then go bold on the final hold to the next tenth. You always go bold on wind — under-holding is the most common reason a hit becomes a miss.
Once you know your number, the actual wind is just a multiple of it. For a 6 mph gun:
- 6 mph×1your range constant, straight up
- 12 mph×2double the hold
- 18 mph×3triple the hold
So a 500-yard shot in 12 mph for a 6 mph gun is 0.5 × 2 = a clean 1 mil. You can do that one out loud before the wind changes its mind.
Wind rarely comes straight across. Don't grind fractional math into your range constant — solve the full value first, then cut it.
That 500-yard, 12 mph hold is 1 mil at full value. Quartering wind? Halve it to 0.5 mil. Just off the corner? Quarter it. It's far faster to hold a full value and chop it than to figure out "what's 75% of my constant" from scratch. Solve big, then trim.
If I have to reference a cheat sheet, I'm not using gun number.
Three Things That Move Your Gun Number
If any of these change, your number isn't your number until you've reconfirmed it. Most shooters don't recheck — that's why their "6" stops working the moment they fly to a match at altitude or pick up a new lot of brass.
Bullet ballistic coefficient
High-BC bullets cut through wind better. Different bullet means a different wind-drift column on your range card, which means a different gun number. Even staying on the same bullet weight, switching brands or picking up a new lot is enough to move things at distance. If anything about what's leaving the muzzle has changed, pull a fresh card before you trust the old number.
Muzzle velocity
Same rifle, same bullet, hotter load — different drift. Time in flight changes how long the wind has to act on the bullet, so velocity walks the gun number. Barrel length, powder charge, cold mornings and hot afternoons — any of it can push your number a click. Confirm the chrono is honest. Then walk the dope and verify where the tenths actually line up across distance.
Atmospherics
Phil's 6.5 Creedmoor is a 6 mph gun at sea level. Drop him in Cody at 5,000 feet of density altitude and the same rifle becomes a 7 mph gun — thinner air, less drift, same shooter doing the math wrong if he doesn't recheck. Carry the card for the conditions you'll actually shoot in. Not the ones you zeroed in.
This is a ritual, not a someday. The first thing Phil and John did at a recent match was grab atmospherics, look at their muzzle velocity, and ask: what's our gun number for this specific location? That happens before the first stage, every time — not after a few clean misses tell them the old number quit working.
Spin drift and Coriolis are not gun-number problems.
Look back at the formula at the top of this page — range constant times wind multiple. That is the whole equation. Nothing in it accounts for spin drift, Coriolis, or which way the earth happens to be turning. If you're thinking, "well, left-to-right is a 7 mph gun, right-to-left is an 8 mph gun" — by the time you've finished the thought, the squad with the simpler system has two rounds downrange. Gun number is the snap call. Save the refined math for shots with time and opportunity, and run the ballistic solver instead.
Here's where a cheat sheet does earn its place — not for gun number itself, but for splitting the wind across two shooters. Phil and John both ran the same 7 mph gun. So Phil took the low pair on his sheet and John took the high pair. Between the two of them they cover a wide wind band fast, and whoever's bracket matches the call takes the shot.
Half value? Each shooter just cuts his own pair in half — Phil's 4 and 6 become 2 and 3. Same formula, two sets of hands, twice the wind covered.
One Call. Different Guns. Same Hit.
Inside a section running the same rifle and the same load, one mil hold fits every shooter — that's the formula's original advantage. But the same teams also run mixed calibers: a .300 Win Mag next to a .308 in a gas gun next to a .308 in a bolt gun next to a 6.5. Those rifles hold different mil values for the same wind, and a spotter calling mils has to translate his hold for every gun on the line. Gun number is what bridged that. Stop trading mil values. Start trading a single mph value. Let each shooter convert through his own number.
Carry that idea to a civilian team. Four shooters running .223, .308, 6.5, and 7 SAUM. Their mil holds for the same wind are all different — but the wind itself is the same. Gun number lets the spotter call "hold 4 mph" and every shooter on that line reaches into his own table for his own correct hold.
Listen to how it actually sounds on the line: "Hey, what'd you hit with?" "Four mile an hour." Boom — same. He holds his 4, you hold your 4, and you both put a round on the same target. Nobody's translating mils across four different rifles.
Mils talk to physics. Gun numbers talk to humans.
Holds shown already gone bold — rounded up to the next tenth.
Two Targets, Two Calls, About Four Seconds Each
This is Steve running a 6 mph gun live on the trigger cam. No Kestrel, no solver. Range, first number, gut-check, send. Walk it with him.
- Target 1 — the pig
Ranges it: 566 yards. In his head he rounds up to 600 to go bold, so the very first number out of the gate is 0.6. Wind's coming from the left.
He puts 0.6 left on center and asks the only question that matters: do I really think it's blowing that hard? Feels like it died down. So he cuts the full value in half — 0.3 left — and breaks the shot.
- Target 2 — the blue
Ranges it: 690 yards. Round up to 700, first number is 0.7. Same gut-check — doesn't feel like a full value, feels like about half, so 0.35.
He can't dial 0.35, and you always go bold, so it rounds to 0.4 left. Elevation dope was 4.7. Range, number, halve, bold, send — and he's onto the next target before most shooters have the Kestrel out of the pack.
Here's the part the formula doesn't say.
You can memorize your gun number tonight. You can carry a clean range card, a calculator that rounds up to the next tenth, and a spotter calling honest mph values into your ear. None of that puts a round on steel until you've made the call a few hundred times in real wind and reverse-engineered what the conditions were telling you off the impact.
Gun number is a starting rung, not the ceiling. Most shooters begin by calling wind in a 5 to 6 mph bracket. With reps it tightens — 4, then 3, then 2, then 1 — and calling it down to the single mile per hour is the biggest separator between top competitors and everyone else; that's 10,000-plus rounds a year of cost. Eventually you stop reaching for the formula at all. You look at a 140 ELD-M target, range it, and just know: that's a three-tenths wind call. Gun number is the on-ramp to that intuition, not a replacement for it.
Steve says it cleaner than anybody: "Don't be afraid to miss. That's the whole point. We learn more from our misses than we do our impacts." The first hundred wind calls will tell you more about your rifle than the cheat sheet ever will. Get the number cold. Then get on a range and start missing on purpose.
Build your gun number on a range with us.
Reading this is step one. Step two is putting rounds against steel, missing, and reverse-engineering the conditions until the number lives in your head. Bring your gun to one of our courses — we'll get you there.