Kit887

Any time I try to run minecraft with mods (usually Tekkit Legends or Hexxit - (I've tried FTB Ultimate Reloaded but that doesn't even get anywhere into the game) it will load and play for a bit until I do something like kill an animal, try to look thru catalogue - anything not super basic - and then will crash. I've had error messages saying I don't have enough RAM but I'm running a 16GB with at least 7GB free - I have it set to 3G for java 64bit, latest version and the java seems to be the problem. I've updated all my drivers, uninstalled and reinstalled both java and mods - no luck. Any suggestions on why it's not working and how to solve? :c just want to play mods with friends