The JP Enterprises Silent Capture Spring Systems is a one-stop solution for both the buffer and buffer spring, and has an option for those who use the Law Tactical folder. Ultimately the relationship between the gas entering the system and the pressure of the buffer spring are in contention, and exist in a balance.

For those with a later-model Daniel Defense MK18, the polymer dust cover will not close with the JP Bolt Carrier. Instead, the JP Enterprises enhanced bolt carrier group meets a better end-goal by focusing on operation and durability. The locking lugs take an increased beating with the higher pressure when unlocking, and the increased lubricity of Titanium Nitride coated parts make them easier to clean, but the diminishing returns lean towards a cleaner operation, and less toward decreased parts wear. The Bolt and Bolt Carrier Groups have two opportunities for enhancement: coating and construction. The additional pressure increases the violence of the bolt carrier group movement, further complicating producing a rifle that can fire softer ammunition unsuppressed and higher pressure while suppressed without issues. Contrary to 2010 video game physics (RIP MW2), attaching a suppressor does not itself slow down the projectile, but adds pressure at a rate less than inches of barrel length. This also translates into a harsher unlocking of the bolt, and faster rearward motion of the BCG. The MK18 achieves reliable cycling by opening up the gas port to compensate the short dwell time. The 10.3 inch barrel of the Daniel Defense MK18 achieves an average velocity above 2,500 fps when using a standard NATO 62 grain 5.56 round (M855 Ball/green tip).

Too little pressure, and the bolt carrier group does not cycle, too much pressure, and the felt recoil goes up as well as the rate parts wear out. If a MK18 is fundamentally a short barreled AR15, three elements come into play on the front end of the rifle or large frame pistol: the length of the barrel, the location of the gas port, and its location on the barrel.

10 inch quad rail mk18