Serbu Firearms' new upper receiver for the AR-15 platform uses a different operating system which eliminates the need for a buffer and buffer tube! The operating rod houses the main spring, and the gas system uses a fixed piston. The result is a gun that runs much cleaner, is more reliable, and can be more compact than any AR-15 which uses a buffer tube. The SU-15 fits any AR-15 lower receiver and uses standard AR-15 bolt heads, firing pins, cam pins, barrels and barrel extensions, eliminating worry over these highly-stressed parts. Parts commonality is also increased. Initially, we are offering the SU-15 in two receiver lengths and four different barrel choices. The standard receiver is 14.75" long while the short receiver is 12.55". Initial barrel choices are as follows: 7.5" 5.56mm, 16" 5.56mm, 9" .300 BLK, 16" .300 BLK. A full-auto capable version will be available in both receiver lengths but will cost more and be shipping at a later date than the standard versions. At this point you are buying a $200 non-refundable deposit to get your place in line for the SU-15 at the $795 introductory price; deliveries will start in April. Please note in your order which receiver length you'd like and what your barrel choice is. The price is for a complete SU-15 Upper Receiver which includes the bolt assembly, buffer, and barrel assembly. Note that the final product will vary slightly from the accompanying pictures and also note that optional items like optics, slings, and buttstocks may be shown but are not included. We will be offering our side-folding buttstock shown on the short receiver version soon. Please be aware that the short version is considered a short-barreled rifle and is only legal if registered per the National Firearms Act. The SU-15 can be configured as a pistol, but adding a buttstock to a version with a barrel under 16" without prior NFA registration is illegal. Feel free to make suggestions or ask questions in the notes section of the shopping cart when you order. Please don't delay....after 2/20/15 the price will go to $1050.