At least 10 per rifle. 10 is a combat load. Have another 10 in reserve (per rifle) to replace bad mags as you train with the first 10. Number your mags so you know exactly which one is fucked up when it starts inducing malfunctions. If you do competitions, it is handy to have 2 Pmags coupled together to monopod off of, or in open division 40 or 60rd Pmags are useful to get through a stage without reloading.
At least 10 per rifle. 10 is a combat load. Have another 10 in reserve (per rifle) to replace bad mags as you train with the first 10. Number your mags so you know exactly which one is fucked up when it starts inducing malfunctions. If you do competitions, it is handy to have 2 Pmags coupled together to monopod off of, or in open division 40 or 60rd Pmags are useful to get through a stage without reloading.