barrel porting

[Beefullo]

Ok, I am opretty sure that the little holes on the sides of barrels are called porting bu tmaybe I am just stupid. Anyways, is this beneficial? It seems to me as soon as the first hole comes the ball would lose all pressure behind it. The stock minimag barrels have no porting. Many othr barrels do have it. WHich is better?

[-Carnifex-]

Without porting the barrel will explode, thusly killing everyone.

[rikkter]

more porting = less efficient
less porting = more efficient

more porting = more quiet
less porting = more loud

[SG Avenger]

Originally posted by -Carnifex-
Without porting the barrel will explode, thusly killing everyone.

Oooh.. I want to see a flatline blow!

[athomas]

The ball accelerates until it reaches the porting in the barrel. At that point the air pressure escapes out the holes due to less resistence than pushing the ball. The result is that the ball only accelerates in the nonported section and immediately starts to slow down at the porting. The dispersion of air out 360 degrees around the barrel also allows the noise to be reduced because there is less of a blast.

Using the mag as an example, a good efficient barrel is around 11 inches long without porting. If the barrel is ported after the first 6 inches then the gun needs to shoot more air to accelerate the ball faster so that it reaches its final velocity in a shorter distance. This makes it more inefficient.

[Kevmaster]

yep. SP or other barrel manufacturers claimed porting makes a barrel more accurate, WRONG.

It will make it quieter and it will make it less efficient. I personally shoot a Lapco barrel, which has 11" unported, its loud as hell, but i coulndt care

[JAM]

don't forget the most important thing- it looks cool.

;)

[rikkter]

yeah, thats why i dont like my JJ edge kit. theres way too much porting, i'v been thinking of blocking off some of the holes.
my old JJ barrel (that ceramic one) is nice, it doesn't have porting til the end, which i like, has the efficientcy and isn't as loud

[nt2004]

didnt tom kaye write an article in APG about barrel prting a while ago or am i thinking of someone else?

[Kevmaster]

what did it say?

[nt2004]

i couldn't find a link to it at APG's site but it talked a lot about why theres porting. He said something about the ball feeling humongous amounts of g-forces and that proting helps releive the strain on the ball by venting gasses. Someone should ask him for a link or summary or something. I'm not sure if i still have the issue.

*EDIT* i think the name of the article was 50,000 fps, which evidently refers to the force on the ball as it first enters the barrel

[nt2004]

its the June 2002 issue. the article is 50,000 fps and for somereason it doesnt appear in the past articles section of their site

[FalconGuy016]

Originally posted by nt2004
its the June 2002 issue. the article is 50,000 fps and for somereason it doesnt appear in the past articles section of their site

Conspiracy against AGD

[nt2004]

i found the issue. its called barrels & pressure: barrel theory

long article. i still cant find any links to it

[Beefullo]

So the 8" unported minimag barrel is no good???

[Ov3rmind]

Anyone remember those Ramrod barrels? Now THATS porting!

Anyway, yeah what everyone said is true. A moderately ported barrel will be less efficienct, but not horribly so.

[athomas]

Originally posted by Beefullo
So the 8" unported minimag barrel is no good???

The 8" barrel is good, just not as efficient as an 11" barrel on a mag. The level 10 may change that a bit though though. Barrel efficiency vs length varies from gun to gun depending on the air delivery behind the ball.

[aut911]

one thin i need to clear up for you guys though. If the barrel in question is ported and has the same size bore throughout then it will be less efficient then the same barrel without porting.

but the thing about most barrels is the fact that they are stepped. In other words if you inlarge the diameter of a barrel to where the bore no longer touches the ball, its as if the 16 in ported barrel is a 10 inch non ported barrel for efficiency.

my .02

aut

[Kevmaster]

or take a lapco for instance that has a 14" straight bore unported.

[aut911]

not sure but i think the velocity would be lower than with a 10 inch barrel that isnt ported. Again i am not sure due to the fact that i dont have a non ported 14" barrel around here to compare.

aut

[Star_Base_CGI]

The porting is supposed to make the gun quiter. My barrel doenst have any porting. It just has a Muzzle brake.

If you dont have any porting you just have all the air come out the end. Uts actually more effiecient to have no or little porting. POP!

[Lohman446]

However, I read this somewhere, and it made sense then.

The shorter the effective length of the barrel (the point before the first ports) - the more consistent the velocity out of it - so ported barrels are more accurate, but not because of the porting doing anything other than making the barrel effectively shorter.

[anthrakz]

I remember reading that article Tom wrote. Here's a summary of what was written. Porting has an inverse relationship with efficiency. A ball will decellerate once porting begins. But porting is not all bad. Porting in the form of a muzzle brake is beneficial. In an unported barrel, the blast of air only has one place to escape, out the tip, right behind the ball, and this creates turbulence potentially knocking the ball off course once it leaves the barrel. With a proper muzzle brake the air blast is vented out out and away from behind the ball allowing it to leave the barrel almost unscathed. A good example that I can think of it the Lapco barrels. It has porting on the last 1" of its effective barrel length and also flares out after it. Effective barrel length also depends on what output pressure your gun shoots at, because air behind the ball will lose its pressure as it the ball goes down the barrel giving the air more space to fill. After a certain point your ball will decellerate, porting or no porting, due to the pressure beginning to drop off and the friction of the barrel walls. It was said in the article that a barrel of about 8"-10" was best for most applications since most guns shoot at around 200psi give or take 50psi, this was also the part where Tom says that low pressure guns (ie. low pressure autocockers) are a myth since most guns shoot at 200psi. It was a good read, and came in handy when choosing barrels. Makes you think twice about buying that shiny $100 Boomstick over the $50 Lapco, no? I knew there was a reason I preferred my old JJ hardchromes

[gamarada717]

I remember the Ramrod barrel.....I heard it actually amplified the sound on some guns.

[jpm]

I'm pretty sure this (http://www.automags.org/resource/tech/tomstech/01_barrel_eff.shtml) is TK's artical on barrel efficiency. Good read. Don't believe the hype, believe the science.

[nt2004]

yeah thats the one. couldnt find it on APG's webstie though