The specific weight plays a role in recoil, accuracy, and sometimes reliability in your particular firearm. Some guns will shoot one load better than another, and different loads may hit at different points of aim. This is due to the barrel length and twist rate, as well as the general parts fitment of your firearm.
Caliber Closeup: A Look at 9mm Bullet Grain Weights - The Shooter's Log
The 9mm cartridge has been in development since 1901 and is now available in several different bullet grain weights with unique properties.
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