A Data-Driven Approach To Precision Rifles, Optics & Gear

Berger Bullets Bearing Surface Variation

One of my friends recently told me they sort bullets by both weight and length of their bearing surface (the part of the bullet that comes in contact with the barrel, illustrated below).  I hadn’t thought of that before, but you could see how variations in the bearing surface length obviously impact the amount of barrel friction on the bullet and therefore cause variations in muzzle velocity. For virtually all of my precision shooting I use Berger bullets, and I wondered if there was even any measurable variation in their bearing surface because their quality control is so much tighter than other ...

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Detachable Magazine Dimensions & Max COAL

The table below contains the maximum Cartridge Overall Length (COAL) for popular detachable magazines for rifles.  This is important to consider when picking a rifle cartridge to ensure you have enough clearance to “chase the lands”, which just means as your chamber throat begins to naturally erode from use you seat your bullet further and further out so that it maintains the same relative position with the rifle lands.  Many people start with their COAL almost maxed out in their magazine, and as their chamber throat starts to wear they are forced to choose between loss of accuracy from not ...

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Portable Reloading Press Plans

I wanted to create a portable reloading press stand that I could mount my full-size RCBS Rockchucker Press or smaller RCBS Partner Press to.  The plans I came up with were simple to build, used easy to find materials, and the finished product has worked exactly like I was hoping.  The stand is very strong and stiff, which is critical when designing a reloading press mount.  It is ergonomic and natural to use on either a table top or a work bench surface.  I just use one or two Irwin Quick-Grip Clamps to hold it securely to the surface.  The stand has “window cutouts” ...

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7mm Rem Mag Load Development Part 4: 5 Shot Groups

I’ve already done quite a bit up to this point in my load development.  At this point I know I want to try to find an accurate load for Berger’s 168gr VLD over Hodgdon’s Retumbo powder and I’m now zeroed in on a very specific range of powder weights that seem to be very tolerant of slight pressure variances.  You can see the previous posts for how I got here. My next step is to test 5 shot groups in very granular powder increments. Jump to another step: Part 1: Bullet Selection & Real-World Velocities Part 2: Audette’s Ladder Test Part 3: Optimal Charge Weight Part ...

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7mm Rem Mag Chamber Print

When the 7mm Remington Magnum was originally released, it was met with overwhelming demand.  Every rifle manufacturer rushed to offer rifles chambered for the new cartridge, and in the rush some of the chamber dimensions varied slightly from different manufacturers.  This variation in the 7mm Rem Mag chamber dimensions has carried on to today, and there is still more differences in the chamber dimensions than for virtually any other rifle cartridge. What’s a chamber print? A “chamber print” is an illustration of the chamber reamer used to cut a rifle’s chamber.  It contains all of the key dimensions related to ...

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7mm Rem Mag Load Development Part 3: Optimal Charge Weight

After I identified a promising range of powder weights using Audetter’s ladder test, my next step was to use Dan Newberry’s Optimal Charge Weight (OCW) Method to offset the “scatter node” drawback inherently present in the ladder test.  To learn more about that, read this article comparing the OCW method with the ladder test. The OCW method is based on the observation that there are some loads out there (like Federal’s match ammo for the 308) that shoot really well out of just about any rifle.  How can one recipe shoot so well out of so many different rifles?  Dan Newberry believes accuracy of ...

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7mm Rem Mag Load Development Part 2: Audette’s Ladder Test

The first step in load development for my new custom 7mm Rem Mag started with gathering the real-world velocities I could expect out of three quality long range bullets I was considering. I then used those velocities to compare the ballistic performance between those three bullets, as well felt recoil during the test rounds. I eventually decided to pursure further load development for Berger’s 168gr VLD bullet over Hodgdon Retumbo powder because it struck the right balance for me between the competing characteristics (recoil, barrel wear, flat trajectory, low wind drift, ideal energy for medium sized game, etc). For more ...

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Standard Atmospheric Pressure for Long Range Shooting

I’ve found myself needing to reference this info a lot while making data cards. It indicates the standard atmospheric pressure at different elevations. Pressure can vary quite a bit from the “standard” listed here, and although that won’t make much of a difference at short or mid ranges … when you get out to 1,000 yards or beyond it can make a noticeable difference. If you know the specific pressure the day you are shooting, it could really help your ballistics tables be more accurate. Having a Kestrel that can measure the instantaneous pressure is the best solution. Altitude (ft) ...

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7mm Rem Mag Load Development Part 1: Bullet Selection & Real-World Velocities

The first step in load development for my new 7mm Remington Magnum (with a 27″ barrel) was to get a basic idea for the real-world muzzle velocities I could expect out of a few different high quality, very low drag bullets, so that I could compare them ballistically and decide which to pursure for further load development. I decided to try out the three bullets listed below after reading a great article on 7mm bullets by Nathan Foster. I actually took all of these readings with a BRAND NEW BARREL (some of the first rounds out of it), so they ...

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Custom 7mm Rem Mag

I recently had a custom rifle built that was chambered as a 7mm Remington Magnum. I plan to use it as a dual-purpose rifle: Precision rifle matches (target shooting out to 1000 yards) Hunting (primarily whitetail & mule deer and the occasional wild hog) I did a ridiculous, almost embarrassing amount of research before landing on the 7mm Rem Mag cartridge. After losing a deer last year, I wanted to make sure it had enough energy to put an animal down quickly. There is no such thing as overkill. With that mindset, I actually started by looking at the 300 ...

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