Complex sentence: The M2 carbine was logistically compatible with the millions of M1 carbines in U.S. service, and offered longer range, better accuracy and better penetration than (pistol caliber) submachine guns like the Thompsons and Grease Guns.
Split into simpler sentences: The M2 carbine was logistically compatible with the millions of M1 carbines in U.S. service. And, offered longer range, better accuracy and better penetration than (pistol caliber) submachine guns, like the Thompsons and Grease Guns.