The Firing Line Forums

Go Back   The Firing Line Forums > The Hide > The Dave McCracken Memorial Shotgun Forum

Reply
 
Thread Tools
Old January 23, 2010, 01:18 PM   #1
Super-Dave
Senior Member
 
Join Date: February 1, 2008
Location: Florida
Posts: 795
Why doesn't shotgun porting reduce muzzle rise?

Over all everyone on this site seems to agree that porting a shotgun barrel does nothing for the muzzle rise and is just a gimmick.

My question is how come it does not work? It works for pistols and rifles and the theory seems sound enough that it should work on shotguns as well.


How come it does not work?
__________________
If you want a vision of the future, imagine a boot stamping on a human face - forever.

George Orwell
Super-Dave is offline  
Old January 23, 2010, 01:28 PM   #2
oletymer
Senior Member
 
Join Date: September 9, 2005
Posts: 335
It does reduce muzzle rise a little. It does not work as well as with handguns and rifles because the gas pressure is much lower.
oletymer is offline  
Old January 23, 2010, 02:26 PM   #3
B.L.E.
Senior Member
 
Join Date: December 20, 2008
Location: Somewhere on the Southern shore of Lake Travis, TX
Posts: 1,901
Ports or muzzle brakes work by taking the propellent gasses out of the recoil equation by redirecting them up or backwards.

With high power rifles, the powder gasses are a significant percentage of the total stuff that comes out of the barrel. In the more extreme varmint calibers that approach 4000 fps, the gunpowder actually begins to outweigh the bullet, by directing these gasses backward, they can nearly cancel the reaction caused by accelerating the bullet. It may even be possible to overcancel and cause the gun to recoil forward.

With shotgun loads, you are accelerating about 500 or so grains of shot using only 18 to 25 grains of powder so a muzzle brake on a shotgun has much less effect than it does on a rifle.
Ditto with rifles that shoot heavy bullets at shotgun velocities like the .45-70, the bullet so outweighs the powder charge that eliminating the powder gasses' recoil contribution only makes a small difference.
B.L.E. is offline  
Old January 23, 2010, 05:17 PM   #4
Shawn Dodson
Junior member
 
Join Date: December 16, 1998
Location: Titusville, FL, USA
Posts: 1,030
Vent ports (compensator) at the top of the barrel do very little to reduce muzzle lift. There is not enough "retro-jet" thrust.

Whereas a muzzle brake has a chamber with a flat wall that the propellant gases directly impinge. The impingement thrust "pulls" the the gun forward, reducing recoil and muzzle lift. After striking the flat surface(s) the gases can vent in any direction, sideways or upwards. Venting upward does not assist in reducing muzzle lift.
Shawn Dodson is offline  
Old January 23, 2010, 05:25 PM   #5
Microgunner
Senior Member
 
Join Date: March 6, 2006
Location: Central Florida
Posts: 2,925
I had both barrels ported on the Browning Citori I use for Sporting Clays. Noticeable improvement.
__________________
Proud NRA Patron Member
Microgunner is offline  
Old January 23, 2010, 05:38 PM   #6
oletymer
Senior Member
 
Join Date: September 9, 2005
Posts: 335
With proper porting gases are vented up and rearward. It does reduce slightly muzzle lift in a shotgun. If someone tells you different they don't know simple physics.
oletymer is offline  
Old January 23, 2010, 06:09 PM   #7
red caddy
Senior Member
 
Join Date: August 17, 2009
Location: South West Florida
Posts: 119
works for me.

I've made several modifications to my 32 in. Hi rib Citori trap gun, it's used mainly for bunker trap and live bird shoots.

I ported the under barrel, just before the screw in chokes, (8 .060" holes .375" O/C) and noted about the same recoil reduction as lengthening the forcing cones provided, a side benefit was the total stop of muzzle rise with 1 OZ. loads.

Really helped my doubles scores and greatly reduced the fatigue factor across the board.
red caddy is offline  
Old January 23, 2010, 06:12 PM   #8
BigJimP
Senior Member
 
Join Date: February 23, 2005
Posts: 11,338
I disagree - I think porting makes a big difference / and it works very well. I think it reduces muzzle jump at least 25 - 50 %.

All 5 of my target guns in 12ga and 20ga are ported / even my semi-auto Benelli's are ported in both 12 and 20ga - and its a big improvement in muzzle jump vs some of my older O/U's that don't have the porting. My O/U's are all Brownings / and the ports are angled / but I don't think that's the issue.

Last edited by BigJimP; January 23, 2010 at 06:46 PM.
BigJimP is offline  
Old January 24, 2010, 12:48 AM   #9
noyes
Senior Member
 
Join Date: December 27, 2008
Posts: 1,032
I know adding some weight to the front will reduce muzzle climb. With some more weight on the other end for balance , then felt recoil is reduced to where you will feel the difference.

Check out different types of shotguns .Some types weigh more than others.....less felt recoil.
trap...................wt.
skeet.................wt.
target................wt.
hunting...............wt.
home defence......wt.
noyes is offline  
Old January 24, 2010, 05:05 AM   #10
zippy13
Senior Member
 
Join Date: August 23, 2008
Location: SoCal
Posts: 6,405
Super-Dave, I beg to differ with your initial premise, there is no consensus on barrel porting at this forum. At best, several of us have agreed to disagree. IMHO, porting is not a gimmick, it's applied physics.

Here's a + 1 to BigJimP's response.

Go out and shoot 1000 pairs of comp 12-ga doubles without ports and then do again with a ported gun. Then you'll have an intimate understanding of muzzle rise. Porting may not turn a B-class shooter into an overnight Double-A; but, it let's you get on the second target a little quicker.

Another AA Skeet shooter wanted to know why I was able to shoot my doubles quicker than he could. The quicker you can shoot your second shot in doubles, the more time you have to adjust, if something goes wrong, before the target goes out of bounds. He knew I been taking special effort with my doubles and wanted to know if would share some of what I'd learned. We took a Skeet field for the afternoon for some practice. I followed the basics my mentor had passed on to me: Take the first target at the same spot you'll be be breaking the second one and minimize your gun movement. Hold out as far a possible before calling for the first target. See the lead with the first target, shoot, keep your face on the gun while you watch the first target break, acquire the second target, see the lead, shoot and follow thru. There's less than a second between shots. The part about keeping your head on the stock and seeing the first target break before you make your move on the second one is very important and takes less that 1/10-second. I shared everything I could with my buddy and he was shooting respectable pairs by the end of the day. I thought he'd be satisfied with his progress. He'd adapted well to the new timing and revised hold and break points, but he was unhappy because he wasn't faster. What I didn't point out at the time: He was shooting a K-80 with un-ported barrels and I was using a P-Mirage with ported barrels.
zippy13 is offline  
Old January 24, 2010, 09:08 AM   #11
B.L.E.
Senior Member
 
Join Date: December 20, 2008
Location: Somewhere on the Southern shore of Lake Travis, TX
Posts: 1,901
Well, of course porting is effective in a shotgun. The effect is just not as dramatic as it is with high powered rifles.

The gasses that push the bullet out of the barrel weigh exactly as much as the gunpowder that generated these gasses. A 12 gauge one ounce (437.5 grains) of shot propelled by 18 grains of Red Dot means that only 18 grains of gasses are available to redirect backwards to cancel the recoil.

Compare that to a .300 Weatherby Magnum loaded with a 115 grain bullet propelled by 90 grains of powder. The powder nearly weighs as much as the bullet and you can almost make the gun recoil-less. Just be sure to wear earplugs!!
B.L.E. is offline  
Old January 24, 2010, 09:45 PM   #12
Shawn Dodson
Junior member
 
Join Date: December 16, 1998
Location: Titusville, FL, USA
Posts: 1,030
I have two 18" barrels for my Remington 870, both are factory barrels modified by Hans Vang (Vang Comp). Both have had their forcing cones back bored. One has vent ports along the top of the barrel, the other doesn't. There is no difference in muzzle lift between the barrel with the compensator vent ports and the barrel without.
Shawn Dodson is offline  
Old January 24, 2010, 09:53 PM   #13
lambertsteeth
Senior Member
 
Join Date: January 18, 2010
Location: steel city
Posts: 272
I actually think it does. The thing is, it's hard to notice. While your gun (usually 12 gauge) is going bang, I am gonna blink. I am also so busy looking for my second target and bringing the gun toward the target that I really don't notice what the muzzle is doing.
If my guns didn't already have this feature, I wouldn't spend my money to have it done.
I've shot my Benellis (ported) with the ports taped up. I noticed a very small difference. It was minimal.
__________________
One of God's greastest gifts to man is Dog.
lambertsteeth is offline  
Old January 24, 2010, 10:07 PM   #14
oneounceload
Junior member
 
Join Date: April 18, 2008
Location: N. Central Florida
Posts: 8,518
For muzzle rise, NOT to be confused with recoil reduction, porting MIGT have some minor value. I see NO value in porting the top barrel, a la Browning, as there is no third shot to acquire.

I have the utmost respect for Zippy and Jim, but I really don't place much value in porting - even for targets. If you THINK it works, then it works, whether true or not. The few studies and high-speed photography I have seen do not, IMO, show a discernible adjustment in muzzle rise.

It seems funny that P guns, Zippy's favorite, do not come with porting, yet they are THE choices for some of the fastest shotgun games known - bunker and pigeons.............

Again, if YOU think it works, go for it. If I find a gun I want that has it, I will not NOT buy it because of the porting, but I will never spend extra $$$$ to have it done..
oneounceload is offline  
Old January 24, 2010, 11:29 PM   #15
zippy13
Senior Member
 
Join Date: August 23, 2008
Location: SoCal
Posts: 6,405
Quote:
Originally Posted by oneounceload
It seems funny that P guns, Zippy's favorite, do not come with porting, yet they are THE choices for some of the fastest shotgun games known - bunker and pigeons………….
My P-MX(SC)3 came with factory "Tula'' port/choke system -- a very nice little shooter, and the flat sides provide a canvas for the engraver's art. The heavier P-Mirage and Mirage based ones came without factory ported barrels.

It should be noted that my friend, oneounceload, and I have had been on opposite sides of the muzzle rise debate from the get go. However, we do agree that: porting does reduce recoil and the recoil reduction is a greater factor in porting that any reduction of muzzle rise.
zippy13 is offline  
Old January 25, 2010, 06:26 AM   #16
B.L.E.
Senior Member
 
Join Date: December 20, 2008
Location: Somewhere on the Southern shore of Lake Travis, TX
Posts: 1,901
Quote:
I see NO value in porting the top barrel, a la Browning, as there is no third shot to acquire.
There may be a sporting clays station somewhere where you might elect to shoot the top barrel first.
B.L.E. is offline  
Old January 25, 2010, 09:30 AM   #17
lambertsteeth
Senior Member
 
Join Date: January 18, 2010
Location: steel city
Posts: 272
Porting both barrels on an o/u is usually done to give the option to shoot either barrel first. Some folks would rather just shoot the other barrel than change chokes on a clays course.
__________________
One of God's greastest gifts to man is Dog.
lambertsteeth is offline  
Old January 25, 2010, 09:49 AM   #18
oneounceload
Junior member
 
Join Date: April 18, 2008
Location: N. Central Florida
Posts: 8,518
And yet the porting on the top barrel is not the same as the one on the bottom barrel. I shoot sporting every week - I do not change chokes, but, as required, I may change which barrel. Since I only shoot light target loads in these guns, muzzle rise is minimal at best.

Seems funny to me that field guns typically do not come with porting, yet the guns are lighter, you're usually shooting heavier loads - which would mean more muzzle rise. If there was ever an argument for porting, it would be there.

But that's OK, these discussions are mild and kinda fun.

And sorry, Zippy, I'll give you a smidgen on porting for muzzle rise, but I won't give you anything about it reducing recoil - Heavy gun plus light load in a properly fitted gun makes that happen!....
oneounceload is offline  
Old January 25, 2010, 11:01 AM   #19
PJR
Senior Member
 
Join Date: May 31, 2000
Posts: 1,127
A few years ago I experimented with a Beretta 390 and two barrels, one was ported while the other wasn't. In blind tests between the two I could not tell a difference in either recoil or muzzle rise. They seemed exactly the same to me.
PJR is offline  
Old January 25, 2010, 11:56 AM   #20
Shawn Dodson
Junior member
 
Join Date: December 16, 1998
Location: Titusville, FL, USA
Posts: 1,030
Depending on where the ports are located from the muzzle (for example, a distance ranging between 3.5" - 7"), with a shotshell that achieves 1200 fps muzzle velocity, the vent port "retro-jet nozzles" are "thrusting" for a period of time between 250-500 MICROseconds (1/4000th - 1/8000th second).

Increased muzzle velocity decreases "thrust" time.

Decreased distance between the vent ports and the muzzle also decreases "thrust" time.

Food for thought.
Shawn Dodson is offline  
Old January 25, 2010, 12:39 PM   #21
zippy13
Senior Member
 
Join Date: August 23, 2008
Location: SoCal
Posts: 6,405
PJR,
Come on, now, let's play fair... a Beretta 390 is not the gun for your test. Let's start with something that has some significant recoil. The B-390 starts out as one of the lowest recoiling stick guns around, and you wonder why you couldn't detect the difference with a ported barrel. The difference is going to be very subtle in that gun. Perhaps you might not be aware of the difference; but, at the end of the year your average may be a little higher with the ported barrel.

Anyone out there with a M-500 with a light plastic stock that has a significant recoil? Mossberg offers a porting service for $35. I'm surprised Super-Dave, hasn't already run a comparison thread on this one. I can see it now: "The Mosssberg thirty-five dollar difference: rip-off or fantastic bargain?"

Sorry to get in your face, PJR, about the R-390. You were working with what at was hand. Given the choice between an R-390 and porting an M-500, I suspect most folks would opt for the R-390 if cost wasn't a factor.
zippy13 is offline  
Old January 25, 2010, 01:01 PM   #22
BigJimP
Senior Member
 
Join Date: February 23, 2005
Posts: 11,338
I agree OneOunce - it would make sense for field guns to be ported as well / and personally I shoot my sporting clays / Skeet guns in the field ...so mine are.

OneOunce and Zippy know this for sure .....but remember guys, before you move the gun for a 2nd target - you need to shift your eyes first, find the target, then move the gun ......you don't move the gun, then find the target ...

I like porting / and think it helps a lot ....but when, or if, you Tube a gun ...send it to Briley or Kolar for fitting of a full length set of tubes ... the tubes will cover up the ports in the original barrel. In the best system, with a separate carrier barrel for the tubes ( bored out, so with the tubes in it, it weighs exactly the same as the 12ga barrer - the 12ga barrel would still be ported. But when I put the "carrier barrel" on the gun / with the tubes for 20, 28ga or .410 ....eve if the carrier barrel originally had ports in it ...they would be closed by the tubes.

Not that Krieghoff and Kolar won't do anything you want (for a price ) / but in general, I think its fair to say, they prefer not to port their barrels ...even on Trap guns / that will probably never be fit with a "set of tubes" .....

But I still like my ported Browning O/U's .....and in Sporting Clays, I usually change my chokes at each station ...... and I alternate my shells between 8's, 7 1/2's , and 9's ( but usually 1 oz of 8's ) ....( I paid for a full set of chokes, and I intend to use them all ...) .....
BigJimP is offline  
Old January 25, 2010, 05:51 PM   #23
PJR
Senior Member
 
Join Date: May 31, 2000
Posts: 1,127
Quote:
Come on, now, let's play fair... a Beretta 390 is not the gun for your test. Let's start with something that has some significant recoil. The B-390 starts out as one of the lowest recoiling stick guns around, and you wonder why you couldn't detect the difference with a ported barrel. The difference is going to be very subtle in that gun.
Quote:
IMHO, porting is not a gimmick, it's applied physics.
Zippy, these two posts by you are contradictory. If it's applied physics than the physics should apply equally regardless of the gun.

Sure the 390 is a soft shooting gun but if there is a reduction of the scale you and others claim it should be felt with the 390 as much as any other gun. The physics of a one ounce load versus a 1-1/8 load are noticeable in a 390. If the porting difference is so "subtle" that I couldn't notice it then why bother having the work done.

I've owned ported guns and think the benefits are minimal to non-existent. The 390 comparison was the closest I could come to a fair test because all other factors were equal. I've also shot a ported MX8 that is similar (although not identical) to mine and wasn't sold on the expense of having my gun ported.

If recoil reduction is the objective money is better spent on proper stock fit. That has made a noticeable difference on my guns including the soft shooting semi-autos.
PJR is offline  
Old January 25, 2010, 07:04 PM   #24
BigJimP
Senior Member
 
Join Date: February 23, 2005
Posts: 11,338
Zippy can speak for himself ...( he's a big boy ) ...but I don't see his comments as contradictory either ...

But recoil reduction isn't a factor in "porting" in my opinion / just muzzle rise... In my opinion, there is no significant reduction in recoil from "porting".

I agree a poorly fit gun will probably give a shooter more felt recoil ( especially if it smacks them in the face / recoils into the cheek bone vs sliding under it, etc ..) but all those things are different issues than trying to find something to stop or reduce the muzzle rise ....which, in my opinion "porting" does very well.

But its hard to prove / and a lot of experienced shooters like OneOunce ...say there is no effect from porting ....so its an interesting discussion.
BigJimP is offline  
Old January 25, 2010, 07:33 PM   #25
lambertsteeth
Senior Member
 
Join Date: January 18, 2010
Location: steel city
Posts: 272
I absolutely agree that porting does not reduce recoil.
__________________
One of God's greastest gifts to man is Dog.
lambertsteeth is offline  
Reply

Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -5. The time now is 10:37 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
This site and contents, including all posts, Copyright © 1998-2014 S.W.A.T. Magazine
Copyright Complaints: Please direct DMCA Takedown Notices to the registered agent: thefiringline.com
Contact Us
Page generated in 0.12798 seconds with 7 queries