We copied an AR 15. The barrel is 1/4" foam w/1" high density foam pad for thrusting and slashing. The butt is 2" high density foam for serious thrusting and slashing. You have your choice of no trigger guard-trigger only, or a trigger guard that is not complete at the front for disarming without breaking fingers- a bit more realistic.
Weight can be added for more realism. Remember-these are for training and sparring, and the idea is to gain experience WITHOUT injury, so the weight CANNOT be the same as a real weapon!