Porting size?

[Patron God of Pirates]

Anyone know what size bits are typically used to drill barrel ports?

[athomas]

Port sizes? That one is up for debate. A large number of smaller ports should be more quiet than a smaller number of large ports. That's typically been my experience. I'd say use 1/16" to start. If that isn't large enough, go up to 3/32". Remember, its easy to drill it larger, but you can't drill it smaller.

[Spider-TW]

It also has to do with the design of your porting (hole layout) and the inner diameter of your ported section.

I think 1/16" is the smallest I've noticed. Then you have the AGD crown point and various muzzle-brake designs.

There's probably some trade-offs around air turbulence, noise, length, and clean-ability.

[Patron God of Pirates]

Thanks guys. What I'm actually trying to figure out is ports vs. barrel step in terms of area.

.695 area = 1.5174677915002098790084183202086 (largest Freak and presumably comparable to freak fronts)
.679 area = 1.4484030186036918644540555680706 (smallest Freak Insert)

Difference = 0.069064772896518014554362752138

1/16" port area = 0.01227184630308512983774470071594

Not sure what this means other than that my theory of porting being a bigger factor (in efficiency) than ID step is (at least mathematically) inaccurate. There are other things to consider though. With ID step the air is at least still escaping in the same direction as the ball. It doesn't jive with my real world testing.

[athomas]

0.695 ID area = 0.379in^2 (largest Freak)
0.679 ID area = 0.362in^2 (smallest Freak Insert)
0.700 ID area = 0.385in^2 (tip ID)

difference = 0.023in^2 from tip to smallest ID barrel insert

1/16" hole area = 0.003in^2
3/32" hole area = 0.007in^2
1/8" hole area = 0.012in^2

You can see that there is only 0.023in^2 of area around the ball for air to escape if using the largest barrel ID and the smallest ID numbers for paintballs. Eight 1/16" ports would exceed the area so more air would escape the ports than around the ball. Generally there are quite a few more ports than that in most barrels and the ports are generally larger in most barrels. Just going to the next larger size of only 3/32" ports, the area more than doubles so just over three ports would exceed the area for air escaping. If you use a tip with a smaller diameter, the amount of difference for air escaping through the ports is even greater. This means that much more air escapes through the ports than around the ball.

[Patron God of Pirates]

Just trying to find the ideal barrel from an efficiency only standpoint. a 10" un-ported fibur with freak boring gave me a noticeable up-tic in shots per fill. But if the bore step is equivalent to 8 1/16" ports then what I really want is a 9" or 10" control bore. I've only seen them that long for the FLASC kit.

[Syko89]

Lapco barrel are straight bored I believe