I've suffered this for ages, sad to see its still unsolved.

Originally posted by The Door to Guf:

its as simple as i stated, i cant change the amount of bullets in the mag if i have Juniez's Classic Weapons Pack installed. i know this as i directly changed the amount in my game directory

Juniez Classic Weapons pack for some reason changes names of some of the weapons models to be different than in vanilla, so it also includes modified .dmx files to make those models actually work. Unfortunately those same dmx files are also used for edit magazine sizes and some other things, so there is no way you could make those kinds of mods work with Juniez Classic Weapons pack unless you know how to edit those dmx files by yourself. You can blame the makers of that mod for making it this way.

Someone has done this