December 27th, 2018

Chronos by The Numbers — Tips on ES, SD, and Sample Sizes

USAMU Marksmanship Unit Velocity Chronograph Testing Sample Sizes

The U.S. Army Marksmanship Unit (USAMU) regulary publishes “how-to” articles on the USAMU Facebook page. One informative “Handloading Hump Day” article covers chronograph testing and statistical samples. We highly recommend you read this article, which offers some important tips that can benefit any hand-loader. Visit the USAMU Facebook page next Wednesday for the next installment.

Chronograph Testing — Set-Up, Sample Sizes, and Velocity Factors

Initial Chronograph Setup
A chronograph is an instrument designed to measure bullet velocity. Typically, the bullet casts a shadow as it passes over two electronic sensors placed a given distance apart. The first screen is the “start” screen, and it triggers an internal, high-speed counter. As the bullet passes the second, or “stop” screen, the counter is stopped. Then, appropriate math of time vs. distance traveled reveals the bullet’s velocity. Most home chronographs use either 2- or 4-foot spacing between sensors. Longer spacing can add some accuracy to the system, but with high-quality chronographs, 4-foot spacing is certainly adequate.

Laboratory chronographs usually have six feet or more between sensors. Depending upon the make and model of ones chronograph, it should come with instructions on how far the “start” screen should be placed from one’s muzzle. Other details include adequate light (indoors or outdoors), light diffusers over the sensors as needed, and protecting the start screen from blast and debris such as shotgun wads, etc. When assembling a sky-screen system, the spacing between sensors must be extremely accurate to allow correct velocity readings.

Statistics: Group Sizes, Distances and Sample Sizes
How many groups should we fire, and how many shots per group? These questions are matters of judgment, to a degree. First, to best assess how ones ammunition will perform in competition, it should be test-fired at the actual distance for which it will be used. [That means] 600-yard or 1000-yard ammo should be tested at 600 and 1000 yards, respectively, if possible. It is possible to work up very accurate ammunition at 100 or 200 yards that does not perform well as ranges increase. Sometimes, a change in powder type can correct this and produce a load that really shines at longer range.

The number of shots fired per group should be realistic for the course of fire. That is, if one will be firing 10-shot strings in competition then final accuracy testing, at least, should involve 10-shot strings. These will reflect the rifles’ true capability. Knowing this will help the shooter better decide in competition whether a shot requires a sight adjustment, or if it merely struck within the normal accuracy radius of his rifle.

How many groups are needed for a valid test? Here, much depends on the precision with which one can gather the accuracy data. If shooting from a machine rest in good weather conditions, two or three 10-shot groups at full distance may be very adequate. If it’s windy, the rifle or ammunition are marginal, or the shooter is not confident in his ability to consistently fire every shot accurately, then a few more groups may give a better picture of the rifle’s true average.

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December 27th, 2018

Cartridge Comparison Guide Covers 250+ Cartridges

Cartridge Comparison Guide

Cartridge Comparison GuideThe Cartridge Comparison Guide is a remarkably comprehensive 340-page, spiral-bound book. Covering over 250 cartridges, the Second Edition of the Cartridge Comparison Guide is the product of many years of labor by Andrew Chamberlain, a Utah-based hunter. Andrew says his Guide “compares every factory available cartridge from the 17 calibers up to the 50 caliber cartridges”. (Sorry, most wildcat cartridges are not covered.) Chamberlain’s Guide also compiles cartridge data from major ammunition manufacturers such as Barnes, Federal, Hornady, Norma, Nosler, Remington, Sierra, Swift, Weatherby, and Winchester. It shows the optimal velocity achieved for each bullet weight and calculates bullet energy, recoil, and powder efficiency. Large color photos illustrate handgun and rifle cartridges.

The Cartridge Comparison Guide provides data for thousands of cartridge/bullet/velocity combos. Quick reference data sheets and ballistics charts cover Trajectory, Velocity, and Energy out to 500 yards. The Cartridge Comparison Guide also offers a firearms lexicon, plus Appendices covering Cartridge Selection for Game Animals, Bullet Selection/Design, Bullet Expansion, Wound Channel Characteristics and more.

New Content in Second Edition of Cartridge Comparison Guide
The Cartridge Comparison Guide (Second Edition) costs $29.96 plus shipping and tax. CLICK HERE to visit the Online Store where you can order the 340-page book. Here’s what’s new in the Second Edition:

  • Addition of Shotgun Ammunition (Both Slug and Shot loads).
  • Momentum Calculation for all Rifle, Shotgun and Handgun loads.
  • Integration of Shotgun Slug Ammunition with Center Fire Rifle Data Tables.
  • Factory Load Summary Added (Shows manufacturers and loads produced).
  • One factory load and one hand load for every bullet weight available in each cartridge.
  • Over 90 pages of additional ballistics content (roughly 35% more than in First Edition).

Cartridge Comparison Guide

Great Resource for Hunters
One of Chamberlain’s main goals in creating the Cartridge Comparison Guide was to help hunters select the right cartridge for the job: “This started as a personal project to gather information on the more popular cartridges commonly used for hunting. I wanted to find the best all-around performing cartridge and rifle that a guy on a budget could shoot. I began comparing cartridge performance, versatility, bullet selection, powder efficiency, recoil generation vs. energy produced, standing ballistic data for different environments….”

Giant Cartridge Poster for Computer Wallpaper (1665×1080 pixels)
Here’s a great illustration of hundreds of cartridges and shotshell types. For dedicated reloaders, this would work great as desktop “wallpaper” for your computer. CLICK HERE for full-size image.

cartridge poster

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December 27th, 2018

Save 15% Now on All McMillan Fiberglass Stocks

McMillan 15% Off stock fiberglass sale december 29 2018

Here’s a great deal if you need a high-quality tactical, F-Class, benchrest, high power, silhouette, ELR, or hunting stock. Right now McMillan Fiberglass Stocks is discounting ALL its stocks 15% (fifteen percent). That’s right, EVERY McMillan rifle stock in inventory is on sale NOW for fifteen percent (15%) Off. But you must act quickly! This special 15% Off Sale concludes at 11:59 pm MST on December 29, 2018. So you have two more days to shop. Remember, this sale applies to ALL McMillan stocks, but the sale ends at 11:59 PM on 12/29/2018. Use Code STOCK2019 during check-out to save 15%.


To Save 15% Use Promo Code STOCK2019 at Check-Out »

McMillan 15% Off stock fiberglass sale december 29 2018

Note — Along with the 15% Savings, Free Shipping applies to orders over $50, standard ground delivery in the Continental USA. Shipping charges on previous orders will not be reimbursed. This offer cannot be combined with other promotions or offers. Offer expires December 29th at 11:59 pm MST.

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