Barrel Porting Facts

Ires

Ires

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I have been asked this question a few times (outside of the forums) and thought it would be something you guys may want to have posted here. Now that I am frequenting the forums I'll try and contribute from time to time.

The issue at hand is the effects of porting the barrel on any given Pistol. slide porting does not count as it does not effect the ballistics of the projectiles while it does effect the cycling of the slide (far too little to cause any noticeable effects). I will post information on porting a 4.4 inch P226 barrel and show effects on ballistics at different porting lengths. The overall effect can be applied to all calibers as a reference; although the actual numbers may change the overall ratios should remain the same.

Load - 115 Grain JHP
5.8 grains of Unique for a tested un-ported velocity of 1224 FPS
1.090 overall length
.129 Ballistic Coefficient

UNPORTED

Maximum pressure is reached within 1/5th of an inch and achieves 31,110 CUP of pressure with a projectile velocity of 390 FPS

At 2 inches the pressure is at 15,000 CUP with a velocity of 995 FPS

At 4 inches the pressure is at 6,500 CUP with a velocity of 1140 FPS

At 4.4 inches the pressure is at 4,500 CUP with a velocity of 1224 FPS


PORTED within half an inch of barrel crown

all numbers the same until projectile reaches porting. at this point the velocity is 1126 FPS and CUP is roughly 6,400. pressure is released and the projectile is actually measured to have a muzzle velocity of 1090 FPS most likely due to friction at the remaining unassisted portion of the barrel.

PORTED within 1.5 inches of barrel crown

All numbers same as above until projectile reaches porting. at this point the velocity is 1014 when it reaches the first port at 3 inches with a CUP of 9,800. at this point the pressue is released and the bullet travels the remaining 1.5 inches unassisted which caused the muzzle velocity to drop again down to 938 FPS.

PORTED within 2 inches of barrel crown

All numbers again the same until porting is reached. for this last port the velocity of the projectile was at 1005 at which point pressure was at 11,900 when the pressure was released the bullet slowed down significantly through the remainder of the barrel and had a muzzle velocity of 845 FPS

all muzzle velocities were calculated about 3 feet away from the muzzle and the bullets were impossible to keep exactly the same ballistically but I believe you can see the pattern here.

if anyone has any additional questions or anything just post it here and I`ll see if I can help.
 
Have a G34 with 4 port Lonewolf.

No hard numbers, but with the open slide G34 and 4 port barrel the recoil feels to be reduced by around 40-50%. The slide wasn't getting enough ooomph causing countless stovepipes.

I had to increase my load of 3.8 Titegroup/125 gr to 4.4
The max in my book is 4.0

Ejection is now strong, 0 stovepipes, 0 issues.
The increased load did not really affect the recoil as much as I'd thought.
The higher pressure just pushed the barrel down that much more.

Having said that, this has become a stupidly loud pistol :eek:

Picture running headers on a 600 crotch rocket.
 
That`s a hefty load, maybe you could keep track of the Head space measurements over time as you fire that pistol and come back to show any changes that may have occurred as a reoccurring update to this topic. I haven't seen very much information on it and I think that kind of information would be awesome, I sure as hell would appreciate it.
 
Fabulous report! You must work in a research lab to get results like that.

Okay, porting reduces power and reliability while increasing noise to dangerous levels. What is it good for? Why do people do it? I've always wondered.
 
I believe it all started when someone decided they wanted to reduce the amount of muzzle lift they were experiencing with thier pistol, I have no clue where it begin but I do believe the only manufacturer that offers it pre-done is Glock. Other then that my best guess would be that people started doing it for looks as well.

As far as I can tell there is really a huge loss to performance so it's not something I will be doing to any of my barrels, specially when I can still get the "cool" look by doing the slide and leaving the barrel untouched.
 
All speed measurements once projectiles left the barrel were calculated using a PVM-08 in Benicia California and internal measurements were simulated using Quickload 2011, once Quickload information was calculated it was compared to chronograph to make sure the data matched up (which it did) to within +-5FPS (distance from barrel). ill see about scanning the original Docs to post in here, they are full of a bunch of other information calculated at the same facility.
 
Ires said:
I believe it all started when someone decided they wanted to reduce the amount of muzzle lift they were experiencing with thier pistol, I have no clue where it begin but I do believe the only manufacturer that offers it pre-done is Glock. Other then that my best guess would be that people started doing it for looks as well.

As far as I can tell there is really a huge loss to performance so it's not something I will be doing to any of my barrels, specially when I can still get the "cool" look by doing the slide and leaving the barrel untouched.
Click to expand...

Thanks, Ires. You'd think everyone would know by now that to look cool, all you have to do is install side-sights. :cool:
 
Correct me if i a wrong it has been some time

Did not Springfield not offer a factory port in the P9 many years ago

P9 were made by Tanfoglio assembled by Springfield

but not a expert
 
My Glock21sf has a 4 port Stormlake 6 inch barrel, it really brings recoil way down. I bought it to try a 45 super build. With standard 45acp, it feels like I'm shooting light target loads, when using standard ammunition. I don't recall if I chronied it, vs the standard barrel, I don't think I did, but I will, when I get a membership and can go shooting again.
 
definitely chrono that, would love some .45ACP data to compare, PM me the infor if this thread goes dead
 
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