No but a used beater M4 is a whole lot cheaper than a new Mk18 or a new M4 and it's probably been maintained by military armorers it's entire lifespan. Though

No but a used beater M4 is a whole lot cheaper than a new Mk18 or a new M4 and it's probably been maintained by military armorers it's entire lifespan. Though yes, the military firearms tend to be select fire. Probably not a useful feature for police but I can't imagine they use it with any frequency.