Sight Geometry

A Practical Workshop Guide for Gunsmiths

Measure twice. Calculate once. Cut once.

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There is a specific kind of frustration that happens at the bench.

You have the rifle in front of you. You have the bases, the sight elements, the barrel measurements, and a caliper in your hand. Everything seems measurable — and yet the numbers do not always come together cleanly.

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One wrong assumption can lead to the wrong cut.
And once metal is removed, there is no easy way back.

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Sight Geometry was created for that exact moment.

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This practical workshop guide helps gunsmiths, rifle builders, restorers, and serious hobbyists understand, measure, calculate, and verify open sight geometry before making irreversible cuts.

It explains the relationship between sight height, barrel taper, bore axis, sight radius, point of impact, and correction amount in a way that connects directly to real bench work.

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This is not a ballistics textbook.
It is not a manufacturer’s catalogue.
It is a focused guide to the geometry behind correctly fitted open sights — written for the way a craftsman actually thinks through a rifle at the bench.

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Inside the guide, you will learn how to:

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• understand the main geometric lines involved in open sight work
• avoid confusing bore axis, mounting surfaces, and line of sight
• measure sight height and barrel outside diameter at the correct locations
• account for barrel taper instead of relying on a single diameter
• use a practical workshop formula for sight geometry
• understand sign convention before interpreting a correction
• follow a complete worked calculation example
• verify the result before removing material
• apply staged cutting and safety checks before final fitting
• use the companion online calculator to support the calculation process

 

The underlying geometry is classical and has been used for generations by military and civilian gunsmiths. What is new here is its translation into practical base geometry, modern measurement methods, and a companion calculator that removes the need for manual trigonometric work.

 

The guide is built around one principle:

 

Precision begins with understanding. You only remove material once.

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Companion Calculator Included

Every purchase includes access instructions for the companion online calculator developed for this guide.

The calculator follows the same logic, notation, and measurement structure used in the book. It helps translate bench measurements into a correction value while supporting both millimetres and inches.

 

Use it to:

• verify manual calculations
• compare measurements before cutting
• reduce arithmetic errors
• support repeatable sight-geometry decisions at the bench

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The calculator does not replace judgment or craftsmanship.
It simply gives the craftsman a clearer number before the file, stone, or cutter touches the part.

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What You Receive

• Digital PDF guide
• Companion calculator access instructions
• Personal-use license
• Downloadable files delivered after purchase

 

Format: PDF
Language: English
Edition: First edition, 2026
Created by: Alexander Popoff / Popoff Gunmakers

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From the Author

“The calculation tells you how much correction is required. Experience determines where that correction should be applied. This guide exists to bring those two together — at the bench, on the rifle in front of you, before any irreversible cut is made.”

— Alexander Popoff, Gunsmith · Popoff Gunmakers