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View Full Version : Regarding Control Bore Length... AGD?



HyperSnyper
11-15-2001, 05:54 PM
Hello,
This question is directed towards Tom. Tom I remember you had an article about barrel efficiency (http://www.automags.org/resource/tech/tomstech/01_barrel_eff.shtml).

At the end, you stated that a barrel of 8-10" would give best efficiency. You also stated that 2 piece barrel systems (with a control bore of 5-6") gave better shot to shot consistency due to cutting off acceleration abruptly.

The question is, what control bore length gives best consistency. I am thinking of getting a new 2 piece barrel, either a Boomy or the New JT's. The JT's are a new breed of barrel which share similar designs of the Boomy.

When comparing 2 of my friends barrels (Boomy and JT and my J&J) O notuced that the newer designed 2 piece barrels (J&J and JT) have smalled stainless sections.

I used a paper rolled up and pushed it into each barrel. This was my measuring tool for the control bore length. I pushed in each barrel until i noticed the tip of the paper reached the bore change.

The results: Boomy has exactly a 6" control bore. J&J has a 5.5 while my friend measured the JT at 5". The trend here seems to be the newer breed of 2 piece barrels seems to be getting shorter on the control bores.

Is this an effective design to get better shot to shot consistency? Is 5" enough bore length to effectively propel paint?

Just wanted to know your opinion Tom... Longer control bore, or shorter? Or does an 1" more or less control bore not even matter, and doesnt even produce significant diffreences? This is such a hard debate since alot of pros nowadys use BOTH the Boomy and JT.

Hoping I can get some clarity here... Thx in advance...

-HyperSnyper

AGD
11-16-2001, 12:27 AM
In general the shorter the control bore the tighter the velocity grouping but the worse the efficiency. Pick your barrel based on which is more important to you.

AGD

HyperSnyper
11-17-2001, 04:58 PM
AGD,
in general, would shorter length barrels be better for Mags? Or in better words, shorter contorl bores be better for Mags?

The Mags design has no dwell period. The duration of valve opening cannot be manipulated due to the fixed volume chamber. Instead the ball is given a fixed volume with pressure to accelerate the ball until the pressure drops and becomes unusable propellant.

Would you happen to know what length downstream of the barrel til a 400 psi blast nolongers serves to accelerate the ball.

Or atleast at what pressure does gas become useless in it duties to accelerate a ball?

Im really wondering what the best control bore length would be.

Thx in advance (and sorry for all the nosy Q's =))

-Hyper