I did some work on my kwa m4 last week (sorbo, new piston head, aoe, shim, and rewire), and only test fired with my hicap. Low and behold upon arriving to the field on Saturday only a couple of my echo1 midcaps were feeding. I've had these mags for 6+ years and have always fed fine in my kwa, it was quite frustrating and I was worried that I messed something up until I tried my hicap and it still worked. So I spent nearly all day yesterday ripping apart 8 midcaps, cleaning, restretching and baking springs. Now they all work again. It would have been nice to have them working at the game. However I had a backup ak in my bag.