I was having a similar issue. I took out the mag catch and applied super glue on the bottom of the compartment opposite the button and dremeled the top so that it would sit higher on the left side there. Thus hold the mag higher and (I imagine) allow rds to be contacted by the bolt better. Although, it seems I encountered the same issue testing a SS. I applied more glue and dremeled more but have yet to see if it fully fixed the problem. Seems to feed better with the CH, at least. I figure it may have worn down due to friction.
I think epoxy might cause less friction and may last longer but super glue seems to be an okay quick-fix. Like an hr or two to set. This is on ABS, too. So not entirely sure how these adhesives will work on other fils, but I figure it's worth a try when you could fix a prob or drastically fortify for less than $10.
