The KWSI MK27 is a heavily modified M4. Using a new upper reciever. It also has 4 firing modes Safe, Semi Automatic, Fully Automatic and 2 Round Burst. It comes in many color schemes but the only ones it ever had while being used in combat where the following C-09 Siberian Night, C-08 Yukon, C-06 Bosnian and C-05 Estonian.
Designed for MARSOC, DEVGRU and SFOD-D it was classified as the MK27 by the Navy and the other services adopted this designation.The weapon has a chrome lined 8.7 in barrel (220.98mm) and instead of firing the 5.56x45mm M193 or Nato M855 it fires the K-247 5.56x45mm round which uses a barrel with a 1:4.35 twist increasing needed accuracy due to the barrel being so short.