tooly,
did you buy your RSA FCG from RSA? Or was it in your gun you bought? If the latter;
http://www.redstararms.com/index.htm?catalog.htm&1
This link is at their site and it has a PDF of the manual.
As far as the mags go, all my steel mags are realatively loose. I have made a RSA magazine release lever
http://www.redstararms.com/index.htm?catalog.htm&1
and it makes mag changes super easy and super fast. No more fiddling with that damn paddle!!! Its pretty easy yo make. I looked at it on the site, made one out of heavy construction paper till it fit perfect, than cut it out of steel with a jig saw. Bent it with a vise and vise grips, then blued it. Oh...and I took off the left side lever making it right handed only. Just didn't ever need the other side.
Anyway, the Polish synthetic mags (slabsides) I bought fit REALLY tight! But really don't give me that much problems. They have gotten much better with use!