The idea being there are situations were you need the AR close buy but not in hand as in left in the vehicle. You may need to grab it quickly and one less thing to grab is good. Other times you may have the AR in hand and would like an extra mag or two but don't want to go full commando. I'm thinking of it as an alternative to the ever popular left rear pocket carry. I got to thinking of it after reading an article in which an officer had his weapon jam after using a magazine that had been in his back pocket. The mag somehow had gotten a gum wrapper stuck in the feed lips and caused a severe blockage.
This is an excerpt from one of USMC03's posts on another forum:
"A Narcotics Sgt. that works on my Dept. went to a 3 gun match and he was watching another shooter. The shooter's AR15 had been working fine all day, then came up to a stage that required a magazine change. The shooter shot the course of fire and retreived a magazine from his support side rear pocket, inserted it into the AR15, shot and the gun jammed. The shooter cleared the jam, fired another round and the gun jammed again. This happended for several rounds and the shooter had to stop and fix his gun. After examining the gun the shooter had realized that he had a gum wrapper in his pocket and this some how got attached to the feed lip of the magazine, when the shooter inserted the mag and the first round chambered, it carried the gum wrapper into the action of the AR15, thus causing his AR15 to malfunction.
The Sgt. told me that many times he and his crew run out of the office to go serve a small warrant and instead of wearing all his tactical gear he just wears his vest and puts an extra magazine or two in his back pocket. After seeing what happened at this match, the Sgt now makes sure that his pocket is free of any debris PRIOR to putting a magazine in his pants pocket. This is a great thing to learn in training, but would SUCK in a very bad way to have to learn when the bullets were flying both ways. In short train like you will fight."
Read the entire post here:
http://www.co-ar15.com/forums/showthread.php?t=8726
One or two pouches like this already on the belt would eliminate this problem.