Final answer:
None of the presented firearm options (M249, M16, M2, M203) have a barrel that does not overheat with prolonged use. All firearms generate heat with use, which can lead to overheating if not properly managed.
Step-by-step explanation:
None of the options mentioned (a) M249, b) M16, c) M2, d) M203 have a barrel that does not overheat with prolonged fire. It is a common characteristic of all firearms to generate heat during use due to the rapid combustion of propellant. This heat can rise to the point where the barrel and other parts can become extremely hot, potentially causing malfunction or damage. While some weapons may feature design elements aimed at dissipating this heat, no firearm is completely immune from overheating over prolonged use.
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