The Aptus AR-15 5.56 rifle evolved from the popular Paratus rifle and features the same patented internal recoil technology and quick takedown rifle technology. The patented internal recoil system eliminates the standard buffer tube/spring associated with most AR-style rifles, allowing it to be fired with the stock folded. The rifle can be assembled in less than 60 seconds without the use of any tools. It has an left side non-reciprocating charging handle. This patented quick takedown rifle is designed for compact portability and discreet carry. DRD has eliminated the need for an additional upper to change calibers, giving you the ability to change between 5.56mm or .300 Blackout with the swap of a barrel. Does not include extra barrel.