A Page From History: Measuring Groups

by
posted on November 2, 2017
handloading.jpg

From the October 1952 issue of American Rifleman, a question from a reader on how to properly measure shot groups.

What is the proper procedure for measuring five- and 10-shot groups fired in accuracy tests of ammunition and rifles, and in benchrest matches?―Lt. Col. Louis E. Roninger, Oak Ridge, TN.

Answer by L.R. Wallack: Groups are measured from center to center of the two outermost shots. This may be done by whatever means available, and it’s my belief that a man who can properly read a scale can come as close as any but the most precise optical measuring device.

A fast and efficient method with the scale is to measure the total group, outside to outside, then deduct the diameter of one bullet. It is a lot more accurate than trying to center the hole in a tight group.

Record groups sent in to the National Bench Rest Shooters Association are measured on a Bausch & Lomb comparator to 20-power magnification. The target is then measured on a grid for total displacement of paper in the group, the diameter of one bullet is then subtracted. Or, more properly, the displaced paper for one bullet hole is deducted. These readings are very close.

Latest

50Thanniversary SA M1A 3
50Thanniversary SA M1A 3

New: Springfield Armory Limited-Edition M1A 50th Anniversary Rifle

Springfield Armory celebrates 50 years of making the M1A with a special limited-edition model that combines historic significance with modern craftsmanship.

New: MDT Cyke-Pod Case

MDT describes this new case for its Cyke-Pod rifle bipod lineup as a “practical and sturdy carrying solution.”

Results: 2024 USA Shooting Rifle And Pistol Nationals

Rifle and pistol champions were crowned at 2024 USA Shooting Rifle & Pistol Nationals, a week-long event that brought together competitors of all skill levels at Ft. Moore, Ga., Jun. 24-30.

Pistol And Smallbore Only: 1947 National Matches

At the 1947 National Matches, Army shooter Joe Benner became the first competitor at the NRA National Pistol Championship to score more than 2600 points in the three-gun aggregate.

2024 Daisy BB Gun Nationals: Promoting The Spirit Of Competition

At the Daisy BB Gun Nationals, young people shoot and compete with the involvement of adult coaches and families, making it a truly inspiring event. The 2024 competition was the biggest in its 57-year history.

Third Annual Remington Shoot To Cure Fundraiser In Arkansas This September

Remington Ammunition’s 2024 Shoot to Cure sporting clays fundraiser to benefit children’s hospitals and disease research will be held in Lonoke, Ark., on Sept. 20.

Interests



Get the best of Shooting Sports USA delivered to your inbox.