KWA M4A1 feeding issues

[Mongrol]

Hey guys, i just got a KWA M4A1 and am having feeding issues. I load an entire 75 rd mid and for the first 15-20 rounds the bbs just kinda fall out of the barrel or are spit out by another bb. Then after those 15 or 20 they seem to work like normal, until i saw this M4 is supposed to shoot 400 fps. Now they shoot but dont reach the max distance and make a sound as though the gun is jammed. The kinda dull thump that AEGs make when jammed. I had a gun that had a broken O-ring on the piston causing fps drop and that may be it but that wouldnt account for the misfeeding. I talked to Jesse at ASONW and got a lot of info im just checking to see what your guy's input is.

Thanks

[wurger]

Type of mag? KWA's can be super picky about mid cap mags. Does the gun work properly with the stock mag? If it works with the stock mag, your mid cap mag probably isn't compatible with the gun.

[Mongrol]

Same problem with the stock highcap. The mids are the same ones iv used in my friends 2gx M4's and they have the same mags too.

[pappyjump]

With KWAs ingenious 2 piece hopup design, if the springs inside the mag are too tight, it will seperate the hop up and make the bbs feed incorrectly.