Saturday, September 7, 2019

What does an additional 160 feet per second mean in a shotgun shell?

Horizontal axis is distance from the muzzle. Vertical axis is velocity of the pellet. Velocity data from the 5th edition of the Lyman Shotshell Reloading Handbook
There are two answers to the question "What does an additional 50 feet per second in muzzle velocity mean in a shotgun shell?"

The lovers of speed will talk about how it reduces time-in-flight and makes errors in "leading the bird" less critical.

I don't shoot that many birds. Most of my shotgun work is pest control or shooting meat animals wearing fur. Most of my concern involves how the load interacts with the target.

Velocity traces for a #6 lead pellet launched at 1315, 1255, 1200 and 1155 feet per second respectively. #6 pellets chosen because it is a common size used for rabbit/pheasant sized game.
Consider a load of #6, lead shot with velocities at the muzzle between 1155 feet per second and 1315 feet per second. That range of velocities is shown by the bold "I" on the image shown above.

At a range of 20 yards, the difference in velocity shrank from 160 feet per second to 85 feet per second and at 40 yards to a difference of 60 feet per second.

Said in a slightly different way, a muzzle velocity of 1155 fps delivers a #6 pellet at 20 yards with an impact velocity of 875 fps. A shell loaded to 1315 fps delivered that same impact velocity at 27 yards, a net gain of seven paces.

That means that a gain of 50 fps at the muzzle nets the shooter about 2 additional yards of equivalent energy-per-pellet delivered on-the-target.

But wait...if the additional velocity is the result of higher pressures, then more pellets closest to the powder charge will be deformed. Deformed pellets don't fly true and can result in inconsistent patterns. The risk of lower energy-per-pellet in the low speed load is counterbalanced by the likelihood of the lower pressure load delivering more pellets on the target...provided your marksmanship is up to the task.

The take-away is that if you are shooting game in the 20-to-35 yard zone, it is not of great importance whether your shotgun load left the muzzle at 1100 fps or 1330 fps. The target will never know the difference if you can put the pattern on the target.

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