Unfortunately upon closer examining his mod, they missed a really key element... The animations for the TBOGT weapons. I've found a way to port over Niko to either EFLC character and there are no worries about animation. Meaning there's no worries to have about the game crashing when you equip a gun like the aa12.
You see in his, he tried to replace the entire Anim.img, with what I'm doing, you don't even have to touch the animation files... Like this is totally and 100% only modification to the player.ped file. No script or anim alteration required.