"poncho-via" (spelling?) style is what we called that way of slinging our weapon in the marines ('85-'91). it allows operator to swing weapon to front, shoulder and fire. also, water can't get in barrel from rain. we only carried weapon on back in the rear with the gear. when patrolling weapon would be slung with paracord (rifle sling removed, less noise, weight), and carried in front at all times, ready to be shouldered and fired. i carried a bmf on my web gear/cartridge belt, right hand side, paracorded around thigh. when rapelling, fast rope, etc... opposite side, same set up, for cross over draw. this allowed for no obstructions/malfunctions during insertion/extraction of operators. just my opinions/experience.