What exactly do barrel ports do?


August 19, 2004, 04:09 PM
AFAIK, they are supposed to reduce recoil.

Anything else?

Please explain.


If you enjoyed reading about "What exactly do barrel ports do?" here in TheHighRoad.org archive, you'll LOVE our community. Come join TheHighRoad.org today for the full version!
August 19, 2004, 04:13 PM
they also increase noise and make firing from a prone position on sand or soft dirt a pain in the ass.

El Tejon
August 19, 2004, 04:23 PM
Purpose of barrel porting:

1. Produce possible pain in retention shooting.

2. Cause lack of night vision.

3. But, most of all, to look cool in gun rags and ads.:cool:

August 19, 2004, 04:36 PM
Do they increase gunsmith profits? :)

Standing Wolf
August 19, 2004, 05:06 PM
Porting a barrel reduces perceived recoil, which enhances accuracy. I've had a number of barrels ported by the good folks at http://www.magnaport.com and swear by them. Cheap? No? Fast? No. Top quality? Yes. Good service? Yes.

August 19, 2004, 05:10 PM
Reduces perceived recoil. Key word is perceived. Actually does little for recoil, but can signicicantly reduce muzzle flip. Can make for much quicker follow up shots, particularly with higher-pressure cartridges. Certainly louder, but I can notice no appreciable difference in muzzle blast between ported and non-ported revolvers. I have no experience with semi-autos. In a revolver, anything thats kicking out a big enough fireball to matter is going to kick it out of the cylinder-barrel gap as well.

August 19, 2004, 05:19 PM
On a pistol they can significantly reduce muzzle flip making for a potentially more accurate second shot. At night most of them will have the same effect on your vision as a flash bulb.

I put one on an AR and it absolutely makes a difference on muzzle rise, however, the noise to me is magnified and people at the firing range hate you because of the pressure wave that is directed backwards or out to each side.

August 19, 2004, 05:45 PM
When the bullet exits the barrel, there is a certain amount of rapidly expanding gas in the barrel, that upon exiting will create a "rocket engine" effect. It is one of the components of the actual felt (not perceived) recoil of the shot. Any porting that redirects the escaping passes at a non-parallel direction to the barrel will reduce actual recoil. How much reduction is open to debate. If the ports are on the top of the barrel, the porting will serve to reduce muzzle rise. While you may not like it, to deny the physics would be foolish.

I competed for five years at an indoor IPSC club. Low light stages (as well as "I wonder what would happen if we did this" type of testing) repeatidly showed that shooting comped and ported open-class IPSC guns in low-light situations had virtually no negative impact on night vision. Your testing may well provide different results.


Jim K
August 19, 2004, 07:53 PM
There are two main components of recoil. The first is due to recoil from the bullet moving forward, and this is the part we normally think of as "recoil" or "kick". The bullet is a relatively massive object, moving relatively slowly. A second part is the recoil from the gas escaping the muzzle either before (precursor gas and air) or after bullet exit. The latter is a relatively light mass (the gas) moving very rapidly. This results in a "rocket effect" which is part of real (not just perceived) recoil. Since a firearm recoils around its own center of gravity (or the center of gravity of the firearm/shooter system), it generally rises in recoil; that is the main effect recoil reducers try to counter.

The idea of most recoil reducers is to redirect that blast of gas so it either does not add to the recoil or counteracts it. Gas ports that deflect the gas to the side do not counteract recoil, but reduce it by directing some gas in a way that will not contribute to recoil. But if the gas is directed backward (not straight back, obviously, but at a backward angle), the rocket effect pulls the barrel forward, actually counteracting some of the recoil. By aiming the gas port upward, the barrel can be pushed down, also reducing recoil.

The drawback is that any gas deflected backward impacts on the shooter, with noise and "muzzle blast". That is usually enough to limit the desireability of recoil reducers on high power rifles, but they can be useful on pistols where the muzzle is farther from the shooter's face.

Note that the gas escape is not a negligible factor, since it is what "put a man on the moon". A rocket moves forward because of the recoil caused by large amounts of gas moving backward at very high speed. It is as if you were able to suspend a rifle in the air and fire it continuously. The rifle would recoil backward and, if it were given a guidance system and enough recoil, would end up on the moon.


August 19, 2004, 10:19 PM
The primary function of the barrel porting on my P9LSP (CZ clone) is to crap up the action with powder :D Fun to shoot, but my gawd is cleanup painful.

August 19, 2004, 11:16 PM
I have found the ported barrel's purpose in a handgun is to coat your arms up to the elbow with powder residue.

August 19, 2004, 11:22 PM
A ported barrel acts just like it has a muzzle break without the added length. It's a faster second shot as opposed to a more accurate second shot. Less muzzle jump means quicker recoil recovery. Like Jim says, the gasses are directed up and out from the muzzle to do this. Mind you, you can't just drill holes in the barrel. They must be of the correct size and angle to have any effect.
Magnaport did lots of research to get it right. They use Electronic Discharge Machines to make the holes without causing burrs or otherwise damaging the barrel. An EDM uses electricity to literally eat the steel away with a machined carbon electrode.

Uncle Doj
August 20, 2004, 08:57 AM
Keep in mind that "muzzle flip" is caused by the fact that the grip is underneath the barrel instead of in-line behind it. If you were holding the gun directly behind the barrel then all you would get is a push straight back. Since you are holding below the direction of the force it causes a torque around your hand, causing the gun to rotate backwards in your hand. So far I've only seen one attempt at changing the grip/angle of the barrel to change that. Porting is just a way of compensating for the effect. ;)

If you enjoyed reading about "What exactly do barrel ports do?" here in TheHighRoad.org archive, you'll LOVE our community. Come join TheHighRoad.org today for the full version!