May I ask what magazines are being used?
I have a GII hunter and have no problems with P-Mags.
What kind of problem is being experienced?
My GII was badly overgassed causing all kinds of problems. The bolt was moving so fast that it caused the bolt to drop the brass back into the magwell and over-run the magazine without picking up a cartridge. It was knocking the crap out of my brass also, the extractor was bending the rims of the case because the bolt was unlocking and starting the extraction process before the chamber pressure dropped enough to let the brass release the chamber.
I am thinking you may be having the same problems I was having. I installed an Odin adjustable gas block and that made things all better. Other people have installed heavy buffers and heavy buffer springs. I did both. What I ended up with is a GII hunter that functions very well and shoots nice enough that I could easily put a couple hundred rounds through it in a day and not be beat up by the recoil. The GII is my favorite gasser.
I think that DPMS purposely overgassed their rifles so they would function with whatever crap was being fed to it.