Quote:
Originally Posted by Fluid1  That's assuming that the 12" barrel has no graduation and retains the same interior diameter the whole 12 inches.... |
Quite the contrary, even a barrel with an under-bore control segment and an over-bore tip segment is much more efficient than just the control segment.
The point in that is: the gas pressure behind the ball, even if there isn't a tight seal between barrel and ball, still accelerates the ball, to a point.
As an example, users of the extended barrel for the Redux report more shots per 12-gram than with the stock barrel. The extended barrel only adds an inch to the stock barrel's 6.25-inch, and is significantly over-bore.
Quote:
Originally Posted by brycelarson ...control bore length is related to efficiency...
...And the smaller the underbore the shorter it should be...
...in all of our testing no matter what size the bore a 12-14" barrel was the most efficient...
...We know that the ball is still accelerating in the tip of a two piece system - meaning that even 6" of control bore isn't enough - even on high pressure guns shooting extreme underbore... |
My experience backs that up.
With real firearms, serious long distance shooters experiment with slow burning powders to allow the bullet to accelerate along the entire barrel.
When I spoke with Craig Palmer circa December 2006 about barrel lengths for a PPS Blazer, he said "the valve is closed by the time the ball hits 12-inches."
You could increase valve dwell and lower the pressure, to simulate a "slow burn" type paintball launch but that sounds like the start of a lot of experimentation for little return.
I'll stick with as long a control bore as I can find and a barrel around 12" where possible. Biggest return for the least amount of experimentation.
EDIT - kudos to Tech-T for updating their website in response to this discussion:
"We have found that by adding only 1.75 inches of compression length to the majority of barrels and barrel systems ,via the iFit Kit, we can obtain significant increases in accuracy and efficiency."
I can get behind that statement, at least as far as efficiency goes.