Fórum Paintball Cenário

robertseakykr
On to Barrels, overbore does allow air to escape past the ball. That's what gives the average lower induced spins. The shape of the ball creates a venturi with the side of the barrel, and as long as the ball is under acceleration (ie. has a pressure differential front-to-back), the ball will center itself in the barrel via Bernoulli's principle. No paintballs are perfectly round. Most are very ovoid. When you bore-match or underbore, the paintball with try to orient itself into a position of lesser friction by spinning as it travels down the bore. If you have a long control bore, the ball is travelling very quickly towards the end and consequently the orientation spin is correspondingly much faster.

Here is a sample of a barrel test conducted by me that demonstrates the shot spread trend. Unlike most barrel test you see, thanks to this manufacturer I am able to separately test various barrel characteristics independently so useful information can be obtained: http://freepdfhosting.com/2ff851dbb5.pdf
Here is another with 9" barrels: http://freepdfhosting.com/fb0fb97a40.pdf

You can see that the overbores shot tighter groups. You can also see that the shorter control bores begin to shoot more equally. At 2.5" the control bores performed identically. This does come at a cost of lesser efficiency. There are always trade-offs in barrel design and never let anyone tell you that a single barrel is optimal in all categories.
You want efficiency: under-bore, but it will cost slightly in shot spread.
You want tightest shot spread: over-bore, but you'll pay in efficiency.
You want a compromise in shot spread and efficiency: bore-match.