*please sticky* The JAC BV system This is for everyone who has ever wondered why there are still people that use these 20+ year old guns. The BV system, or Bullet Valve, can be found in many systems, but JAC and Asahi seem to be the most popular and simplest., and for good reason. In the JAC system, there is only a small number of moving parts. There is very little metal on metal contact, and the system runs on a regulated external power source*. The most common external power source is a Palmers low pressure regulator, and either a CO2 tank or a HPA tank. Both tanks can be found, and filled at most paintball shops. *the JAC system does have an internal tank to run off of, but it is not recommended. First off, here is an exploded diagram of how JAC internals break down. An external air source enters in through the buffer area. Back here there is also a fill valve just like modern GBBs if you want to run off of the internal tank. It is not recommended to use this, as it doesn't last near long enough for a game, and there is cool down. Here we have the basic internals of the JAC system. Air comes in from the buffer tube, into the valve area, and when you pull up on the trigger, it lets air pass into the mainchamber. Meanwhile, a BB has been fed up into the subchamber, and is resting right behind the mainchamber/barrel O-ring. The above picture shows where the subchamber sits so that it can feed BBs through.