It is not bugged. The finderbricks drop in addition to the usual ones, they don't replace them. They drop more frequently but have much less ammo in them, no matter the weapon used. You can argue now that getting one grenade is worse than getting one shot in voices.. but atm this is how they work. Your usual bricks should still give 4 iirc (and they still drop) Sidenote: how many ammo you get from a normal brick is not determined by magazine size but rather by your max reserves (e.g having the default 4/3 in voices you tend to get many bricks with only one ammo in it, pushing it to 4/4 @ reservesx1 you are guaranteed 2 ammo on the normal bricks)