New Chronograph? Run Your First Ladder

A new chronograph tells you exactly how fast every round left the muzzle. The first time out, the trick is shooting it so the numbers answer one question: which charge is your best load. Here's how to set up a first ladder so the data comes home clean, and what to do with it after.

Start with one question

A first ladder answers one thing: across a small spread of powder charges, which one shoots best in your rifle. Keep everything else fixed — same bullet, brass, primer and seating depth for every round. Seating depth and barrel tuners come later, once you have a charge worth tuning. (The full order of work is in how to find your best rifle load.)

Plan the ladder before you load it

• Pick your charges from current published load data for your exact components. Start at or near the book's starting charge and work up in small, even steps. Stop at the first sign of pressure, whatever the chronograph says.
• Decide how many rounds per charge. Three to five finds the rough zone; plan on confirming your finalist with more rounds later. (How many shots per charge?)
• Write it down in shooting order. In Loadscope, Create New Load lays the ladder out for you — start, step and how many, low to high or high to low — and Tools › Print Ladder Sheet gives you a page to take to the range.

At the range: one string per charge, in order

This is the habit that makes the data usable. Every chronograph groups shots into strings — Garmin calls them sessions, LabRadar calls them series. Start a new string before each charge, and shoot the charges in the order you planned them.

• One charge, one string. Don't let two charges run together in one string, and don't split one charge across two.
• Foulers and sighters are fine. Fire them into their own short string. Loadscope spots a string that's shorter than the rest and sets it aside instead of treating it as a charge.
• One target, or one aiming point, per charge, shot in the same order. That order is how the velocities and the groups find each other later, so you never have to label a target or rename a file.
• Note your distance. Up close, group shape tells you the most; farther out, shot-to-shot velocity starts to show up as vertical on the target.

Getting the numbers off the chronograph

Each chronograph gets its data out a little differently:

• Garmin Xero — plug it into your computer with its USB cable. Loadscope sees it, lists every session on it, and you tick the ones from your ladder. (More on the Xero)
• LabRadar — one CSV report per series on its SD card. (More on the LabRadar)
• MagnetoSpeed — the log file on the V3's microSD card, or the CSV the XFR adapter emails you. (More on the MagnetoSpeed)
• Athlon Rangecraft — its export file comes in the same way.

What a first ladder tells you — and what it can't

Look for a charge where three things line up: steady velocity from shot to shot (a low SD), a small group, and short vertical. Neighboring charges that behave the same way are a better sign than one charge that happened to shoot a tiny group. (What average, SD and ES mean)

Be honest about sample size. Three to five rounds per charge finds a zone, not a guarantee. Load a batch of your pick and confirm it with a longer string before you call it settled.