Porting vs. Muzzle Velocity


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cinteal
November 26, 2008, 10:51 AM
Simply, is velocity lost when a barrel is ported? My question is more in reference to rifles.

Thanks,

cinteal

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matrem
November 26, 2008, 07:46 PM
Can't see how it would lose any velocity,if you're discounting the bbl length beyond the porting.

Sinixstar
November 26, 2008, 07:47 PM
My understanding is no. The porting happens beyond the muzzle - and is just a means to allow the gas to escape over a greater area. The bullet has gone through the same length of barrel, with the same amount of pressurized gas behind it when it leaves.

WardenWolf
November 26, 2008, 07:52 PM
Yes, you do lose velocity over an unported barrel of the same length. A bullet is accelerated by a shockwave of expanding gasses within the barrel. By porting the barrel, you are venting the gasses before the bullet has exited the tube. Once the bullet passes the porting it stops accelerating any meaningful amount. Your effective barrel length, except as as a guide, stops at the porting.

The ideal solution is a muzzle brake, not porting. Because a muzzle brake has little or no effect on barrel length, and can be much more intricately designed to be more effective, you lose nothing except recoil.

gvnwst
November 26, 2008, 07:56 PM
Are yo actually drilling the barrel, or attaching a muzzle brake? Porting the barrel will lose you about 20fps i would think, but if you want that, just get a muzzle brake. If you don't like the look, but like a ported barrel, there are also flush brakes that look like the barrel, but a gunsmith has to install them.

ken22250
November 26, 2008, 08:16 PM
i would go with neither muzzle break, or porting, unless you are shoting a 505gibbs or larger, you really dont need it ( ive shot the .460 wby w/o muzzle break, its gives you a sharp rap on the shoulder, but its well worth it when hunting), i would not get anything ported/ brake installed because of the ear splitting report, i much prefer a well made stock, like that on the A-Square .577 Tyrannosaurus, which (with no muzzle break) is less than that of the .460Wby, just my 2 cents.
ken

matrem
November 26, 2008, 08:21 PM
WOW!
No wonder some folks here get confused.

Leanwolf
November 26, 2008, 08:47 PM
I've been using my Ruger 77 .338 Win. Mag., (first model) since I bought it new in 1974. I sent it to Magna-Port not long after I bought it.

Since, I've killed several elk and Mule deer with it, and have never noticed any reduction of velocity due to the ports. 30 or 40 FPS reduction, perhaps?? Who cares?

Damned sure helped on felt recoil reduction, I assure you. :)

Just my experience.

L.W.

Art Eatman
November 26, 2008, 11:09 PM
There has to be a bit of a loss for a ported barrel, but it shouldn't be enough to worry about. The porting is at a point in the barrel where the pressure has fallen quite a bit. For instance, the pressure at the gas port of a Garand is down to some 2,000 psi from its max of around 47,000 or so. Not much push left on the bullet.

If it's an add-on brake, there should be no loss at all.

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