I must confess that my opposition to carbine or rifle magazines with larger than a 20-round capacity stems from my combat experience as a Marine Corps infantryman during the Vietnam War.
When you're taking incoming fire, and you can't get to cover other than the ground in front of you, you must make yourself as small and low a target as possible.
Magazines larger than 20 rounds place your prone position too high unless you turn your carbine or rifle horizontal when firing. I don't like that position for accuracy either.
In law enforcement, there's usually not a need to lay down a barrage of fire for cover or movement. If the officer can't engage his target with 20 rounds accurately, I doubt that 200 rounds would do him much good. The Marine Corps has defined firepower as the number of hits per minute, not the number of rounds fired per minute.
In addition, the longer you make the spring and curve in the magazine's body, the greater the chance for failure due to the spring or follower hanging up in the body. This is no longer as much of a problem with good quality magazines.
What capacity of magazine does your department issue? What do you prefer? Let us know by submitting a comment below. We'd love to hear your perspective.