I wasnt sure if this was a bug or not, so i decided to post it in help before reporting it.
On the Black mesa wiki it says the 9mm ammo (for the pistol and mp5) should cap at 250 spare rounds but it seems as though it caps at 150 rounds ingame. Same thing for the grenade rounds for the mp5, I seem to beable to carry only 3 total compared to the 5 the wiki says.
Any clarification on this would be helpfull.