October 7th, 2018

Reloading Tip: Bullet Bearing Surface and Pressure

USAMU Bullet Ogive Comparision Safety Reloading
Photo 1: Three Near-Equal-Weight 7mm Bullets with Different Shapes

TECH TIP: Bullets of the same weight (and caliber) can generate very different pressure levels due to variances in Bearing Surface Length (BSL).

Bullet 1 (L-R), the RN/FB, has a very slight taper and only reaches its full diameter (0.284″) very near the cannelure. This taper is often seen on similar bullets — it helps reduce pressures with good accuracy. The calculated BSL of Bullet 1 was ~0.324″. The BSL of Bullet 2, in the center, was ~0.430”, and Bullet 3’s was ~ 0.463″. Obviously, bullets can be visually deceiving as to BSL!


This article from the USAMU covers an important safety issue — why you should never assume that a “book” load for a particular bullet will be safe with an equal-weight bullet of different shape/design. The shape and bearing surface of the bullet will affect the pressure generated inside the barrel. This is part of the USAMU’s Handloading Hump Day series, published on the USAMU Facebook page.

Beginning Handloading, Part 13:
Extrapolating Beyond Your Data, or … “I Don’t Know, What I Don’t Know!”

We continue our Handloading Safety theme, focusing on not inadvertently exceeding the boundaries of known, safe data. Bullet manufacturers’ loading manuals often display three, four, or more similar-weight bullets grouped together with one set of load recipes. The manufacturer has tested these bullets and developed safe data for that group. However, seeing data in this format can tempt loaders — especially new ones — to think that ALL bullets of a given weight and caliber can interchangeably use the same load data. Actually, not so much.

The researchers ensure their data is safe with the bullet yielding the highest pressure. Thus, all others in that group should produce equal or less pressure, and they are safe using this data.

However, bullet designs include many variables such as different bearing surface lengths, hardness, and even slight variations in diameter. These can occasionally range up to 0.001″ by design. Thus, choosing untested bullets of the same weight and caliber, and using them with data not developed for them can yield excess pressures.

This is only one of the countless reasons not to begin at or very near the highest pressure loads during load development. Always begin at the starting load and look for pressure signs as one increases powder charges.

Bullet bearing surface length (BSL) is often overlooked when considering maximum safe powder charges and pressures. In photo 1 (at top), note the differences in the bullets’ appearance. All three are 7mm, and their maximum weight difference is just five grains. Yet, the traditional round nose, flat base design on the left appears to have much more BSL than the sleeker match bullets. All things being equal, based on appearance, the RN/FB bullet seems likely to reach maximum pressure with significantly less powder than the other two designs.

Bearing Surface Measurement Considerations
Some might be tempted to use a bullet ogive comparator (or two) to measure bullets’ true BSL for comparison’s sake. Unfortunately, comparators don’t typically measure maximum bullet diameter and this approach can be deceiving.

Photo 2: The Perils of Measuring Bearing Surface Length with Comparators
USAMU Bullet Ogive Comparision Safety Reloading

In Photo 2, two 7mm comparators have been installed on a dial caliper in an attempt to measure BSL. Using this approach, the BSLs differed sharply from the original [measurements]. The comparator-measured Bullet 1 BSL was 0.694” vs. 0.324” (original), Bullet 2 was 0.601” (comparator) vs. 0.430” (original), and Bullet 3 (shown in Photo 2) was 0.602” (comparator) vs. 0.463” (original). [Editor’s comment — Note the very large difference for Bullet 1, masking the fact that the true full diameter on this bullet starts very far back.]

Permalink Bullets, Brass, Ammo, Reloading 10 Comments »
October 7th, 2018

Darrell Holland Upgrade for RCBS Bench Priming Tool

Priming Tool Holland Perfect RCBS bench mount primer

Gunsmith Darrell Holland sells a priming tool that upgrades the RCBS Auto Bench Priming Tool with key features — including primer seating depth control. If your hand starts to hurt after priming dozens of cases with a hand-held, squeeze-type priming tool, you may want to consider Holland’s invention, which he calls the “Perfect Primer Seater” (PPS).

Holland basically has modified the RCBS lever, adding a precise crush control and a means of measuring depth with a gauge. He claims this gives “an EXACT primer seating depth based on primer pocket depth and primer thickness”. With Holland’s PPS, primer seating depth is controlled with a rotating wheel that limits lever travel in precise gradations. You can buy the complete priming system for $215.00, or, if you already own the RCBS Auto Prime tool, you can purchase an adapter kit (with base, arm, adjuster, and gauge etc.) for $120.00. To order, visit Hollandguns.com. Click on “Reloading Equipment”, and look for the Perfect Primer Seater. Scroll down to the bottom of the page to add items to the shopping cart.

Priming Tool Holland Perfect RCBS bench mount primer

Priming Tool Holland Perfect RCBS bench mount primerUser Review by Tommy Todd
Sierra Bullets’ Chief Ballistician Tommy Todd acquired the Holland Perfect Primer Seater, and gave it a positive review. Todd writes: “This cartridge case priming system allows you to measure the primer pocket depth and adjust the seating tool to match the primer seating depth for a contact fit with a measured lot of primers to the cases you are working with. Mr. Darrell Holland has taken a standard RCBS automatic bench-mounted priming tool and modified it to a new level of precision. The modifications allow you to measure the primer pocket depth, primer height, and with the addition of an adjustable stop on the priming tool achieve precision primer seating, rather than how the primer ‘feels'[.]

If you are already utilizing the RCBS priming tool, Mr. Holland offers an adapter kit to upgrade your equipment. If you are looking for a new priming unit, I suggest giving this product a try. Increasing consistency when seating primers should result in smaller groups[.]”

Permalink Bullets, Brass, Ammo, Gear Review, Reloading 3 Comments »
October 7th, 2018

Free Instructional Videos for Concealed Carry Handgun Owners

Panteo Handgun video concealed carry pistol free

Panteo Productions, producers of firearms training videos, has just released a new series of FREE instructional videos for handgun owners. Co-sponsored by Ruger and Federal, the Handgun 101 video series covers handgun and ammunition nomenclature, handgun functions, basic shooting skills, and the key considerations for concealed carry. The three-part series includes: Intro to Handguns, A Concealed Carry Permit, and Intro to Concealed Carry. Part 1 includes multiple chapters with a ton of information. Combined with Part 2 (20 min) and Part 3 (33 min), this series delivers over two hours of helpful content.

These free videos are available streaming online from the Panteao website, on the Panteao mobile apps for Android and Apple devices, as well as on television from the Panteao Make Ready channel on Roku, Amazon Fire TV, and Apple TV. Click the links below to watch each of the three episodes.

Panteo Handgun video concealed carry pistol free

In part One of Handgun 101, Intro to Handguns, instructor Kyle Harth reviews the firearm safety rules, handgun function (and terminology) for both revolvers and semi-auto pistols. In addition, Harth reviews handgun sizes, ammunition, how to grip a handgun properly, safely storing a handgun, proper training, shooting sports and carrying a handgun. This video is intended to be a handgun owner’s first step in familiarizing himself with handgun operation.

Panteo Handgun video concealed carry pistol free

In Part Two of Handgun 101, A Concealed Carry Permit, instructors Kyle Harth and Massad Ayoob carrying a handgun for self-defense, and the important issues associated with defensive gun use. This video reviews concealed carry, traveling from state to state, prohibited carry locations, the use of deadly force, protection of persons and property, and interaction with law enforcement. If you are considering obtaining a concealed carry permit or live in a state where you can carry open or concealed without a permit, this video is for you.

Panteo Handgun video concealed carry pistol free

In Part Three of Handgun 101, Intro to Concealed Carry, instructor Kyle Harth reviews handgun selection, caliber and ammo choices, methods of carry, belts and mag pouches, clothing considerations, and the importance of training. Remember that the Handgun 101 series is not where your education process ends. Take courses from reputable firearms instructors with understanding of self-defense legal matters. Equally important, go to the range and practice!

Permalink - Videos, Handguns, Shooting Skills No Comments »