There are a lot of variables involved with the number of grains of powder in any given caliber round. Most importantly are the type of powder and the weight of the bullet. After that is the loader's preference as to the velocity of the round. For example, I load a 155 grain .40 caliber bullet using Ramshot Zip powder for a "light" velocity of about 1050 feet per second using 5.3 - 5.4 grains of powder.
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