# OneZero Ballistics Calculator — One zero. Every load. > Precision ballistic calculator for .300 Blackout shooters with environmental corrections. (iPhone/iPad app by Reid Thompson.) - Source: https://appshunter.io/ios/app/onezero-ballistics-calculator/id6753189322 (this page in markdown: same URL + `.md`) - Developer: [Reid Thompson](https://appshunter.io/developer/1842948669) - Category: Utilities, Sports - Price: Free - Rating: 5.00/5 from 1 App Store ratings - Age rating: 4+ - Requires: iOS 18.0 · 10 MB - Languages: American English - Released: 2026-02-24 - Data updated: 2026-10-30 - Monetization: free ## What is OneZero Ballistics Calculator? Zero your rifle with one load and know exactly where a second load will hit, without touching your sights. OneZero is a ballistic calculator for 139 cartridges, from .17 HMR to .50 BMG, made for the range and the hunt. Use it for supersonic and subsonic .300 Blackout, a match load and a hunting load, or any two rounds you shoot from one zero. Or use it with just one. SEE THE SHIFT • Pick a zeroed round and a Round 2, and both fly from the same zero. • The headline shows where Round 2 lands at your distance and the hold to correct it: "12.3 in low · Hold U 11.7 MOA". • Only one load? Turn off the second round, and the headline and dope card show its velocity, energy and time of flight instead. • The solution updates live as you type. YOUR HOLD ON YOUR WRIST • When your buck steps out, there's no phone to dig out: the Apple Watch app has your holds on your wrist. • Range it, turn the Digital Crown to the distance, 5 yards at a time, and read the elevation and windage holds. • Set up target cards for your shooting lanes before the hunt, and each one's hold is a swipe away. • Windage follows the watch's compass, so you can face the deer and read the hold. • Your setup stays on the watch, so it works with your phone left in the truck. • Tap a round to change its muzzle velocity, or the wind to set it. Changes go back to your iPhone. • Weather Updates fetch the weather where you are every 15 minutes while it's open, and today's sunrise and sunset sit beside the clock. READ DOPE AT ANY RANGE • Drag across the trajectory chart for drop at any yard; pinch to zoom, and switch between drop and drift. • The dope card lists up, down, left and right corrections for both loads, plus the shift between them, in MOA or MIL. 4,266 FACTORY LOADS BUILT IN • Browse your cartridge's factory loads, with published ballistic coefficients and muzzle velocities, many with bullet length and a G7 BC. • Search or filter supersonic and subsonic, then tap a load to use it. TARGET CARDS • Add the targets you'll shoot at, each with its distance, angle and direction, and see both loads' holds for every one. • Shoot uphill or downhill: holds are worked out along the line of sight, as your rangefinder reads it. • Point your iPhone at a target to fill in its direction and angle. Give a target a direction, and with the wind's direction set, it gets its own wind clock. TRUE YOUR BC • Add the groups you fired past your zero: the elevation you dialed or where each landed, with your chronograph velocity and that day's conditions. • OneZero fits the ballistic coefficient that matches them all and shows how firmly they pin it down. Use it, or save it to your load. WIND FROM YOUR COMPASS • Use Current Weather fills in temperature, humidity, pressure and altitude, and the wind's speed and the direction it blows from. • Tap Target Direction and point your iPhone at the target, and OneZero works out the wind's clock direction and the shot angle. You can still pick them by hand. PHYSICS YOU CAN CHECK • Standard G1 and G7 drag tables indexed by Mach number. • Air density from station pressure, temperature and humidity, with density altitude and speed of sound shown. • Wind from any direction: crosswind drift by the lag-time method, and head and tail winds in the drag. • Miller stability and spin drift from your cartridge's bullet diameter, bullet length and barrel twist, corrected for muzzle velocity and air density. • Coriolis from your latitude, with its vertical part for the target's direction. • Uphill and downhill shots, with gravity split along and across the line of sight. MADE FOR THE RANGE • Save rifles and loads as presets and switch between them in a tap. • Share a PDF dope card with your loads, ready to print. • On iPhone Duo, see Setup and the live solution side by side, split at the fold. • Dark mode and full VoiceOver support. Always confirm your dope with live fire before relying on it. Weather data provided by Apple Weather. ## Key features - Compare supersonic and subsonic loads - Real-time environmental corrections - Interactive trajectory chart - Detailed dope table - Factory ammo library - Custom load presets - Exportable dope card PDF ## Is OneZero Ballistics Calculator safe? Not enough ratings yet to assess OneZero Ballistics Calculator. ## Is OneZero Ballistics Calculator legit? OneZero Ballistics Calculator has limited verification signals. The AppsHunter Legitimacy Score for OneZero Ballistics Calculator is 58 out of 100 points across 7 verification signals from App Store and developer data. ## Frequently asked questions about OneZero Ballistics Calculator ### What is 300BLK Dope? 300BLK Dope is a precision ballistic calculator designed specifically for .300 Blackout ammunition. It helps shooters calculate trajectories for both supersonic and subsonic loads with real-time environmental data. ### Does 300BLK Dope have ads? No, 300BLK Dope is ad-free. Users can enjoy a distraction-free experience while calculating ballistics. ### What devices does 300BLK Dope support? 300BLK Dope is available on iPhone and iPad devices. It is designed to be accessible on Apple's mobile platforms. ### How often is 300BLK Dope updated? The latest version, 1.5, was released on May 4, 2026. Updates typically include improvements and new features based on user feedback and ballistic data. ### Can I compare different types of .300 Blackout loads in 300BLK Dope? Yes, you can compare any combination of supersonic and subsonic loads side by side. This feature allows for direct comparison of different ammunition performance. ### Does 300BLK Dope use real-time weather data? Yes, 300BLK Dope integrates with Apple Weather to provide real-time environmental corrections for temperature, pressure, humidity, and altitude based on your location. ### What kind of ballistic data does 300BLK Dope provide? 300BLK Dope provides detailed dope tables including drop, MOA corrections, velocity, energy, and spin drift. It also offers an interactive trajectory chart with zoom and pan functionality. ### Is 300BLK Dope suitable for beginners? While designed for precision, the app's clear interface and features like the factory ammo library make it accessible. Its focus on .300 Blackout simplifies the ballistic calculation process for users of this specific caliber. ## Version history (last 5 releases) ### 3.3 — 2026-10-29 Uphill and downhill shots, a card for every target, and BC truing at the range. • Shot angle: enter how steeply you're shooting up or down under Conditions, or point your iPhone at the target and Set Target Direction takes the angle with the bearing. Holds are worked out along the line of sight, as your rangefinder reads it. • Targets: a new tab for the targets you'll shoot at, each with its distance, angle and direction and both loads' holds. Give a target a direction and, with Wind From set, it gets its own wind clock. Aim your iPhone at a target to fill in its direction and angle. • Apple Watch: swipe left for your targets and their holds. Set up your shooting lanes before the hunt, and when your buck steps out the hold is on your wrist. Add or change a target with the Digital Crown and the watch's compass, and it goes to your iPhone too. • True BC: add the groups you fired past your zero (the elevation you dialed, where each landed, and your chronograph velocity) and OneZero works out the ballistic coefficient that fits them, and how firmly they pin it down. Use it in Setup, or save it to your load along with its groups. ### 3.2 — 2026-10-28 More on your wrist, and room for a single load. • Apple Watch: tap a round's hold and turn the Digital Crown to change its muzzle velocity, say to match your chronograph. Tap the wind in the corner to set its speed and where it blows from, or face into it and tap Wind From Here. Changes go to your iPhone too. • Apple Watch: turn on Weather Updates and the watch fetches the weather where you are every 15 minutes while it's open. Wind you set yourself stays until you choose Use Weather Wind. • Apple Watch: swipe left for the setup. The info button is gone. • Only shoot one load? Turn off Compare a Second Round. The headline, dope card, PDF and watch show its velocity, energy and time of flight in place of Round 2. • The dope card shows each windage hold under its elevation hold, so there's no switching tabs, and the headline adds time of flight. • The trajectory chart has axis titles. • OneZero now runs on iOS 18 and watchOS 10 or later: iPhone XS and later, and Apple Watch Series 4 and later. ### 3.1 — 2026-10-27 OneZero now uses your compass for wind. • Use Current Weather now fills in the direction the wind blows from as well as its speed. Tap Target Direction, point your iPhone at the target, and OneZero works out the wind's clock direction. You can still pick it by hand. • On Apple Watch, each round's windage hold now sits under its elevation hold and follows the watch's compass, so you can face the next target and read the hold. The info button moves to the bottom-right corner. • Headwinds and tailwinds now count too. They change the drag, so the drop: a 20 mph headwind lowers a 220 gr subsonic round almost 2 inches at 300 yards. • Coriolis: with your latitude, which Use Current Weather fills in, holds include Earth's rotation, about 3 inches each way at 1,000 yards at 45°. With the target's direction they include its vertical part too, and on Apple Watch they follow the way you face. • Stability now accounts for muzzle velocity and air density, as Miller's rule intends. Subsonic loads read less stable than before, with less spin drift, and thin air at altitude steadies a bullet. • 139 cartridges, up from 66, and 4,266 factory loads, up from 3,891. • About 500 more factory loads now include bullet length for stability and spin drift, and about 250 more have a G7 ballistic coefficient. ### 3.0 — 2026-10-26 300BLK Dope is now OneZero: one zero, every load, for 66 cartridges. • Pick your rifle's cartridge in Setup, from .17 HMR to .50 BMG. Its bullet diameter feeds stability and spin drift. • 3,891 factory loads built in. The Factory Loads page opens on your rifle's cartridge, and you can browse any other. • New Apple Watch app: the holds and drops for both rounds from your iPhone's setup. Turn the Digital Crown to step through distances a yard at a time. Today's sunrise and sunset sit beside the clock, and your setup stays on the watch when your phone doesn't. • Made for iPhone Duo: open it to see Setup and the live solution side by side. The Solution tab puts the headline and a larger trajectory chart beside your dope card and details, split at the fold. Closed, the controls sit along the side so your dope gets more of the screen. • Switching between Light and Dark appearance now takes effect right away. • A smaller Setup title on iPhone leaves more room for your rifle and loads. • New setups default to a 10-yard dope card step. Your current setup and saved rifles carry over as .300 AAC Blackout. ### 2.0 — 2026-10-23 300BLK Dope 2.0 is a complete redesign. • See where Round 2 hits: a new headline card shows the impact shift and the hold to correct it. • Live results as you type. No more Calculate button. • Drag across the trajectory chart to read dope at any distance, with a drift view and pinch zoom. • Dope card with up, down, left and right corrections in MOA or MIL. • Wind drift from a clock-face direction, plus spin drift. • More accurate ballistics: standard G1 and G7 drag tables, with air density from station pressure and humidity. • 134 factory loads from 26 makers, with corrected data. • Pick your rifle and rounds right from Setup. • Use Current Weather now fills wind speed too. • New app icon. ## Apps similar to OneZero Ballistics Calculator | App | Rating | Price | Category | | --- | --- | --- | --- | | [Loadem](https://appshunter.io/ios/app/loadem/id6758661743) | — | Free | Utilities | | [PrecisionLoad Suite](https://appshunter.io/ios/app/precisionload-suite/id6760584719) | 5.0 (1) | Free | Utilities | | [LoadBench](https://appshunter.io/ios/app/loadbench/id6753627760) | 5.0 (3) | Free | Utilities | | [Reloader's Bench](https://appshunter.io/ios/app/reloaders-bench/id6759527000) | 5.0 (8) | Free | Utilities | | [Zima: Ballistics Calculator](https://appshunter.io/ios/app/zima-ballistics-calculator/id6760805492) | 4.0 (4) | Free | Utilities | | [Impact! - Ballistic Calculator](https://appshunter.io/ios/app/impact-ballistic-calculator/id6476831891) | — | Free | Utilities | --- *Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-10-30.*