M4-TYPE carbines are popular for law enforcement these days. They are light, handy, compact and offer a much greater level of performance than any pistol caliber carbine. For this reason, many law enforcement agencies are changing from pistol caliber submachine guns (SMG) for SWAT use to M4A1-type carbines.
For patrol use, a semi-automatic version of the ubiquitous M4A1 is an ideal choice. Ammunition and parts are plentiful and reasonably priced. In fact, one of the greatest strengths of the M4A1-type carbine is its modular capability. It wasn’t originally intended to be a modular weapon, but it became one in the early 1990s when the Special Operations Command (USSOCOM) developed the SOPMOD (Special Operations Peculiar Modification).