Dial in Your Hunting Rifle: Learn How to Build an Accurate DOPE

In this journal entry, MTNTOUGH President Lyle Hebel shares the exact process he uses to create a reliable, field-ready DOPE (Data On Previous Engagement) card for hunting. The process includes chronograph-verified velocity, solver tuning with live environmental synchronization, field verification out to 1,000 yards, and practical redundancy through printed DOPE cards. Read on to learn how to create trustworthy DOPE that you can rely on when it matters most.

This article emphasizes using your chronograph-measured muzzle velocity as a fixed input, then adjusting the bullet’s ballistic coefficient (BC) until the solver’s predictions match your observed impacts.

Creating a reliable DOPE card for hunting is a systematic process, not magic. To ensure consistent hits when it matters, I follow a methodical approach, document everything, and verify data in the field. Below is the step-by-step workflow I use whenever I build or refresh my DOPE card.

The goal is simple: build a dependable, field-ready DOPE so you can make repeatable, ethical shots with confidence and minimal guesswork.

More specifically, this process aims to:

• Produce an accurate ballistic profile (true velocity + tuned BC) that matches real-world impacts.
• Verify and validate that the solver’s outputs equal what your rifle actually does at target ranges.
• Reduce variables and surprises in the field by matching device data (rangefinder, Kestrel) to measured results.
• Provide fast and reliable aiming solutions (holds or turret clicks) so you can engage quickly and accurately.
• Create redundancy: electronic sync for speed, and a printed DOPE for when electronics fail.
• Build a documented record (notebook + printed card) you can trust and update over time.

Success looks like consistent hits (or predictable, small corrections) at known distances, quicker target engagements, and increased shooter confidence while minimizing the risk of a wounding shot.

Gear & Preparation (What You’ll Need)

• A rifle zeroed at 100 yards
• 20-40 rounds of ammo
• A chronograph (to measure true muzzle velocity)
• A ballistic solver app (I use SIG BDX in this example)
• A device for collecting environmental data (I use the SIG Kilo10K, but a Kestrel also works great)
• Targets at distances up to 1,000 yards
• A notebook and pen (always carry a dedicated DOPE notebook)

Step 1 — Zero Your Rifle and Record Your True Velocity

Start by confirming that your rifle is reliably zeroed at 100 yards. Next, fire a string of shots through a chronograph to obtain your true muzzle velocity. While manufacturer numbers can serve as a starting point, measured velocity is what your solver needs.

Be sure to record all details in your notebook, including rifle details, barrel length, ammunition lot, temperature, altitude, and chronograph readings.

Step 2 — Build a Custom Profile in Your Solver App

Create a custom rifle/ammo profile in the SIG BDX app (or your preferred ballistic solver). Enter the following information:

• Measured velocity from your chronograph
• Bullet weight and the manufacturer’s ballistic coefficient (BC; we will refine BC later)
• Zero distance (100 yards)
• Sight height and any other platform-specific inputs your app requires

Sync your Kilo10K to enable the app to retrieve current environmental data. Even if you don't delve into environmental physics now, aligning conditions between your solver and shooting location minimizes surprises.

Step 3 — Test at 1,000 Yards and Adjust

Move to a 1,000-yard target and use the app’s range card to get the recommended elevation (in mils). Take your first shot from a stable position and note the location of the impact.

If you miss, use your reticle to measure the offset from your point of aim to the point of impact, and adjust your turret to bring the next shot on target. After hitting your target, return to the app and change the ballistic coefficient (BC) until the solver’s elevation output matches the turret correction you used.

Why Adjust BC (and not Velocity)?

A bullet's BC is not a static number. The BC value published by a manufacturer is an average and can vary depending on your rifle, barrel twist, and muzzle velocity. Truing the BC based on your own rifle's long-range performance gives you the most accurate data for your specific setup. Velocity has the greatest effect on short-range trajectory, while BC has the greatest impact on long-range trajectory. By addressing them separately, you accurately model the bullet's flight path across its entire range. Since you measured your actual muzzle velocity using the chronograph, leave the velocity constant and tweak the BC until the solver aligns with your real-world impacts. 

Step 4 — Verify Across Ranges (900–300 Yards)

Once you've adjusted the BC to match the 1,000-yard correction, verify your data at intermediate ranges (900, 800, 700, down to 300 yards). Utilize your reticle to measure any remaining offsets and make small BC adjustments as needed. Record each impact, the reticle hold, or turret correction, along with environmental notes in your notebook.

Step 5 — Sync to Your Rangefinder and Load into Kestrel

After verification, sync the confirmed profile to your rangefinder so it can provide instant hold/holdover calculations when you range targets in the field. I also load the same data into my Kestrel for redundancy. Different solvers can behave slightly differently, so be prepared to fine-tune the BC on each device while taking similar environmental conditions into account.

Final Precaution — Print a Paper DOPE

Electronics can fail; batteries can die. As an important final step, print a hard copy of your DOPE card with data in 25- or 50-yard increments and keep it in your pack. This is the simplest and most reliable backup you can carry.

Building an accurate DOPE card involves high-quality measurements, careful verification, and meticulous record-keeping. Always remember to bring a notebook, be methodical, and carry a paper backup—you’ll be grateful when the moment comes to take your shot.