http://www.paintballguru.com/autococker/lpbarrel.htm
Low Pressure Guns and Two Piece Barrels
I have owned my Freak back for my cocker for several months and I am now finally getting a chance to try it out. This past weekend, I tried it at the local field and I ended up proving one of my theories about LP ball acceleration to be true.
The theory went like this: with a LP gun, the ball will accelerate slower than a HP gun. Generally I have found that a HP gun will have the ball reach it's maximum velocity about 4 - 6" in the barrel leaving the ball decelerating for the rest of the length of the barrel. For LP guns the ball accelerates to it's maximum velocity about 8 - 10" in the barrel causing the ball to be decelerating slightly less and also having the ball reaching a slower maximum velocity.
What does this have to do with the Freak? I put my marbs into my freak and was using the .691 insert which matched the marbs best. I fired over the chrono and it read about 250fps @ 135psi, my normal operating pressure for my J&J Ceramic barrel. I ended up having to increase the pressure to 155psi to hit 300fps. While this is not a large amount of pressure increase it did prove my theory correct about where a ball hits it's maximum velocity. To help prove this correct I broke out my old reliable J&J Ceramic and hit the chrono again. 335fps @ 155psi. I reduced the pressure to 135psi and hit 300fps. The Freak barrel as well as my J&J were both 14" barrels.
Why did this happen? The reason for this happening is in a multi piece barrel or multi diameter barrel like the freak, boomstick, All American, etc... the back portion is smaller in diameter and the front is slightly larger as well as the front has porting. As I had said before the HP gun's ball hits it's max velocity about 4 - 6" in the barrel, meaning in the tight portion of the barrel then it hits the front portion of the barrel and the excess air is vented allowing the barrel to stabilize more and making the ball more accurate. In a LP gun the ball has not finished accelerating by the time it hits the second stage of the barrel and air both escapes around the ball causing it to slow slightly as well as through the posts in the barrel making you need to increase the pressure to attain the desired velocity.
While I am not bashing the Freak nor any other barrel, I still use my freak on my Angel, they are, however, an inefficient barrel for LP applications. The reason I opt for a J&J Ceramic is it is a one piece barrel and only has porting at the very end of the barrel, about 2" from the end of the barrel to be more precise. This means that the in a 14" J&J barrel @ 135psi the ball has finished accelerating by the time the ball hits the porting. I am now going to try a J&J Ceramic 16" and see what this does to the velocity, perhaps the 14" barrel is too short for 135psi. It could be that in my 14" J&J the ball has not finished accelerating at 12" when the porting begins. I'll try next weekend.
thats kinda where i was going with this
