As a consumer of commercially available ammunition, I’ve found that some manufacturers don’t care to list their test barrel length, which has at times, been a hindrance to my shooting experience. I would like to express my hope that all ammunition manufacturers will someday readily provide the information about what length of test barrel was used to help create the muzzle velocities boasted on the cardboard box of any given load. Let’s look at some examples of where knowing the test barrel length could help a shooter.
TEST BARREL LENGTH & LISTED VELOCITIES ON AMMO
Some of this issue for the consumer of commercial ammo can be avoided by obtaining a chronometer to measure the muzzle velocity as it comes out of their own barrel. For those that don’t own a chronometer, knowing a baseline velocity that shooters can factor in to know how a bullet will perform from a shorter barrel than that of the test barrel. In this, the year 2020, shooters have a plethora of barrel lengths to choose from, across all types of firearms, and I believe the time has come for manufacturers to list their test barrel lengths.
We’re all aware that a bullet’s terminal performance is affected on a target the further it flies, due to a loss of velocity and energy. I found a prime, documented example of this effect from “Xman,” who is a member at the 68forums.com website. As you can see in Xman’s photo below, the bullets performed differently as the projectile’s velocity continued to drop the further they got from the muzzle of his 18-inch barrel.
Xman’s goal was simply testing how the monolithic bullets would perform with his load data, but he granted me permission to use his photo for the purposes of our topic here. Xman told me that it’s an industry standard to lose anywhere from 25 to 40 feet per second (though I’ve seen slightly higher estimates). Thus, knowing how a given commercial load might fare through your 14 inch barrel as opposed to the manufacturer’s 24 inch barrel might come in handy as to your intended purposes when you pull the trigger. A more in-depth look at the variables that affect velocity drop through shorter barrels can be read HERE.
Ballistic calculators are a great tool that can help shooters stay on target, and being armed with the general rule of velocity loss per inch of deviation from the test barrel length could help shooters know where to start when they plug in the muzzle velocity into the calculator.
OPTICAL BALLISTIC DROP COMPENSATORS (BDC’S)
BDC’s found in Red Dot sights and rifle scopes are typically meant for one (or a group of like-trajectoried) loading, which is, in part based on speed. One example is the Primary Arms ACSS BDC reticle, which is also featured in some Trijicon optics. For the best results, the instructions provide the desired muzzle velocity for various calibers to be consistent with the math behind the BDC. It would be prudent for the shooter to find out what kind of difference they may be starting out with.
Some ammunition manufacturers list their test barrel length, though some are a little more hidden, while other companies don’t list them at all. For now, all I ask is that ammo manufacturers list this information on their website, readily available. Eventually, if enough people agree with me, perhaps having it printed on the box may be a nice touch.
As for our readers, what do you think about this issue? Have you had a hard time tracking down a test barrel length for a commercial loading for pistols, shotguns or rifles?