Porting

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I wouldn't think you'd want a field gun ported - all those holes are just another place for rain, snow, ice, mud to get in the bbl. Not to mention more places for brush or thorns to hang up on.

The recoil energy formula uses the weight of the powder and an estimated 4700 fps muzzle velocity as the component of the recoil stemming from the powder. I don't know how much of the gas is re-directied - maybe 1/2? so you could conceivably see a small reduction in recoil - although the powder mass still has to be accelerated so I don't know that you can totally eliminate the re-directed gas from consideration. I know - this is total recoil energy vs. felt recoil.

I doubt very much that even angled as shown above actually achieves redirecting all the escaping gas backwards - the aspect ratio (length of the hole compared to thickness) would suggest the vast majority of the gas would just jet straight out. Useful for muzzle rise if the ports are oriented near the top of the bbl.
 
And to add to that. Since Remington makes the number one shotgun used in Law Enforcement why is it that they offer no ported Police barrels for the 870 Police model. If these were the performance enhancement that some claim, it makes sence to me that these would be offered on every 870 Police. These processes are not pattented and have been around for many years. I can only conclude that they are not as effective as some want us to believe because it is a very simple process that would generate revenue and it is not being done by leading manufacturers. Sometimes you have to read between the lines and use you head to figure out all this mess.
 
where does recoil begin

A friend of mine who is an avid rifle and shotgun shooter and research physicist maintains that recoil begins at ignition and increases when the bullet contacts the lands in a centerfire rifle. In his opinion ported barrels only allow the release of gases and the recoil is already expended and felt. I have one centerfire rifle, Weatherby 7mm magnum that was factory ported from Germany. I don't notice any muzzle jump when shooting from a rest but the resultant noise and blowback are terrible. For that reason I've never hunted with it. But my Weatherby 300 mag and my CZ 375 H&H are not ported and I don't notice any muzzle jump either.

I believe the comments about reduced felt recoil and reduced muzzle jump are great exaggerated.
 
The recoil energy formula uses the weight of the powder and an estimated 4700 fps muzzle velocity
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HUH???? 4700????

If you Google shotgun recoil calculator, several sites will come up and you can plug in your velocity, weight of shot, etc. and it will calculate the recoil. 4700 fps is starting to get into guided missile territory.............. ;)
 
Thats the formula from the lyman manuals - the 4700 only applies to the powder (gas ejecta). The saami formula is lower - about 1.5 to 1.75 times the projectile velocity. The 4700 would be about correct for rifle, a little much for shotgun.

The formula is in the lyman 43rd edition manual - which I can't find my copy right now. (I found this on line but I'm not sure it's absolutely correct) The Lyman formula for free recoil :

E = 1/2 (Wr / 32) ((Wb x MV + 4700 x Wp) / (7000 x Wr))^2

E = recoil Energy in ft. lbs., Wr = Weight of rifle in pounds, Wb = Weight of bullet in grains, MV = Muzzle Velocity of bullet in feet-per-second, Wp = Weight of powder in grains.

The SAAMI formula is here: http://www.saami.org/PubResources/GunRecoilFormulae.pdf

Essentially the same as the lyman formula - except a little more detail as to what to use for powder/gas velocity
 
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For shotguns (which is what we were discussing here), use this site:

http://www.omahamarian.org/trap/shotshellenergy.html

You will see that most target loads run around 16 ft.lbs or so, heavier field loads a little more. Porting will work on heavy cartridge rifles at uber velocities and on small handguns firing those super magnum cartridges when it comes to reducing muzzle rise, but shotguns are too low velocity/pressure-wise and the guns are heavy enough where it just doesn't really help
 
It is a perennially argued subject. I own 2 ported shotguns. A Beretta AL390 ST, and a Browning Cynergy Classic. Both guns were factory ported. For me it is simply a non issue. People put forth the following arguments:

1. Noisy
2. Doesn't reduce recoil
3. Expensive.
4. Hard to clean

I have polled people at the sporting clay and skeet range extensively about increased noise. No one has ever said that they notice increased noise. I certainly don't whether I am shooting them or someone else is.
Ok, it doesn't reduce recoil. It doesn't increase it. As far as expense is concerned it didn't cost me a cent. Hard to clean? Simple, don't clean the ports. If it does nothing, then what's the point? If it does something then anything in those holes will be blown clear.

Bottom line: I wouldn't pay to have a barrel ported, and I wouldn't reject a shotgun because is is ported.

Finally, this photo from a shotgun class that I took. There's an awful lot of gas pouring out of that Remington 870 with the full Vang Comp treatment for it to do nothing. Draw your own conclusions.
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I have polled people at the sporting clay and skeet range extensively about increased noise. No one has ever said that they notice increased noise. I certainly don't whether I am shooting them or someone else is.
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You won't notice it while wearing hearing protection, but it will become apparent quickly without it. Just don't hunt with a ported barrel unless of course you're shooting migratory birds where eyesight alone is most important. Most certainly don't attempt to use a defense barrel in confined spaces with porting.

Hard to clean? Simple, don't clean the ports. If it does nothing, then what's the point? If it does something then anything in those holes will be blown clear.
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It's not that simple as molten plastic seems almost welded to the barrel in and around these ports which eventually affect the patterns. I have personally seen the affects the residue has on patterning when left unattended.

Finally, this photo from a shotgun class that I took. There's an awful lot of gas pouring out of that Remington 870 with the full Vang Comp treatment for it to do nothing. Draw your own conclusions.
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I have no idea whether or not they reduce recoil in a scattergun, but suspect as mentioned earlier that it's already felt. The only thing I currently have that is ported are some Turkey tubes and they're even more of a bear to clean than barrel ports no doubt due to their extremely tight constrictions.
 
As I read through this, with deference to OneOunceLoad, I realize I was wondering further afield in my comments. I was considering porting relative to rifles and handguns, not necessarily shotguns which I recognize (now even better) don't have the same pressures to contend with, or to re-direct. Live and learn!
 
I disagree with anyone who says that porting shotgun barrels does nothing but spend money. If you look at the above images of the ported barrel you will notice that the ports make fantastic lint traps for the collection of what used to be your new barrel mop.
 
I agree with The Technoid... in this case anyway :D
==================

http://shotgunreport.wordpress.com/2013/05/14/barrel-modifications-2/

Barrel Modifications…
Posted on May 14, 2013 by bcbuck

=snip=
There are four basic barrel modifications: 1) chokes, 2) porting, 3) forcing cones and 4) backboring. Since you asked, here is what the Technoid thinks of all four- Yes, No, Yes, Maybe.
=snip=
 
I know The Technoid personally and shoot with him on a regular basis. He is one of the few gun writers who does not back down from bad reviews or telling it like it is when it comes to shotguns
 
It's not that simple as molten plastic seems almost welded to the barrel in and around these ports which eventually affect the patterns. I have personally seen the affects the residue has on patterning when left unattended.
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I have a hard time understanding this. On both of my ported shotguns, as well as the 870 in the picture the ports are well before the choke. Additionally, I think that most people miss the point of porting on shotguns. It isn't to reduce recoil, it is more to help negate barrel rise to accommodate quicker follow up shots. Not saying that it actually does that, but I think that is more the intention than recoil reduction.

I disagree with anyone who says that porting shotgun barrels does nothing but spend money. If you look at the above images of the ported barrel you will notice that the ports make fantastic lint traps for the collection of what used to be your new barrel mop.
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MrWhipple, I believe that you have presented the one objection to porting that has actual validity.
 
Ask yourself this one question. Why does a gas operated auto shotgun have less felt recoil than an O/U , when both are the same weight, using the same ammo? :neener:
 
Key word is felt. If the gas gun and the O/U weigh the same, then the actual recoil will be the same. Even with two O/Us that weigh the same, differing stock dimensions can also affect the felt recoil
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To understand this better get a copy of Shotgunning: The Art and the Science by Bob Brister. He has some excellent charts using the Remington 1100, if my memory serves me. All of the recoil is there, but it is broken up into 3 or 4 "bumps" rather than 1. You can't feel the bumps because they occur too quickly, but it gives the impression that the recoil is less.
 
I carried 400 pounds of shingles to my roof. Man, I'm strong. 400 pounds.

But, then, it took a few trips.

Recoil is the same, but there is more to recoil than force - it also involves time. I can hit you with a baseball bat with 15ftlbs of force and shove you with the same amount of force. Yet perception will be different (as will the effect of the force upon the body).
 
Snarlingiron,

Was that the Shotgun Class at Tac Pro you attended? How did you like it?

To stay on topic, generally with porting the higher pressure the load, the more gas is moving through the ports and the better the porting works. You will notice much less muzzle rise with 3 Inch or 3.5 Inch Magnums than with 2.75 or Reduced Recoil 2.75.

Unless you shoot nothing but 3 or 3.5 Inch Magnums, IME porting won't make that much of a difference.

Just my .02,
LeonCarr
 
Was that the Shotgun Class at Tac Pro you attended? How did you like it?
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Yes, that was the Tac Pro class, and a friend that took it along with me shot the pictures for an article that was published in one of the gun magazines (I forget which one just now). The picture I posted earlier didn't make it into the article. The class was absolutely top drawer. Bill Davison knows his stuff, and the shotgun course is one of his favorite courses to teach. We went through everything from shell construction to chokes (even the archaic jug choking) as well as re-loading techniques (not shell re-loading, weapon re-loading), long range slug techniques, load one shoot one drills, select a slug drills, stoppage drills, patterning and finally the "Jungle Run". It was a very full three days. Not to mention that it was in August and was about 103.
 
If you're going to calculate recoil using a formula there's more than the weight of the powder and load. You also gotta include the weight of any wads, seal disks, buffer, cards, spacers, and anything else that might be in the hull. It may not hit the target but it does leave the barrel, and it does all add up.
 
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