Bushmaster Firearms, with the help from Remington Arms (a sister company) has made many design changes to the ACR. These were made to meet what the U.S. military requirements. The Remington ACR which is intended for the military market is capable of fully automatic fire. Bushmaster offers a semi-automatic only ACR for the civilian market. Bushmaster says that they will soon have conversion kits which can change the caliber of the rifle.