[blackfoot1]

I had a similar feed issue with my Sun Project magazine. I fixed it by swapping the spring and stopper (plastic guide thing on top of the spring) for parts taken from a TM G-Spec mag. I also rubbed down the inside of the mag with wet and dry paper to smooth out any mold lines. It worked perfectly... For a while.

 

[blackfoot1]

Echo1 have released a metal mag for the M28, maybe this would be an inprovement?

 

[blackfoot1]

I'm telling you (and only trying to help).
I haven't a clue how to link...
I googled "echo1 m28 magazine" and it came up with both plastic and metal mags at echo1usa.com
(It was added to the site/catalog on the 14th of Feb 2011)