For 100cr and 4 mass you may add a butt to any ranged weapon to increase the range by 5. Count the range penalties for a weapon with a butt as +1 per 10 squares instead of +1 per 5 squares. The butt also allows the weapon to be used as a club melee weapon.
Thus you can make a laser rifle out of a laser by paying a measly 100cr and adding 4 mass.
An upgraded butt decreases the difficulty by 1 for Combat skill checks to use the weapon as a club.