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Does porting reduce muzzle jump on an o/u
Yes, significantly 13%  13%  [ 14 ]
Yes, moderately 24%  24%  [ 25 ]
Yes, minimally (almost useless) 30%  30%  [ 32 ]
No (porting is useless) 32%  32%  [ 34 ]
Total votes : 105
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 Post subject: re: Porting and muzzle jump
PostPosted: Fri Feb 29, 2008 10:14 am 
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Posts: 2205
Location: Las Vegas, Nevada
Quote:
1/3rd? If this were true then every single manufacturer of
shotguns (or any firearm) would employ porting. That is just
a crazy assertion. Can I ask how you ran these tests? How
did you control all the different variables? How
did you measure the "1/3rd"?


You don't have any idea of what you speak and it is apparent
from this above quote.

First off, every single manufacturer would not employ porting
just because of my facts presented. Saying this is like
saying every manufacturer would make all guns with 30
inch barrels because they give more velocity than shorter
barrels. Or its like saying all manufacturers would make
10 pound guns because they kick less than 7 pound guns.
And even more to the point if I used your faulty logic I
could say no manufacturer would put ports in if they did not
reduce muzzle rise. So don't make idiotic statements like
that and present it as fact.

Second it is not a crazy assertion, it is fact. Yours is the
crazy assertion.

Thirdly, Yes you can ask how I ran these tests. Maybe you should
have done that before you pronounced them to be crazy assertions.
With no idea whatever of how I did the tests, why would anyone
with brains pronounce the tests as a crazy assertion?

How did I control the variables? Wow, can you maybe think for
two seconds as to what are the variables? In comparing porting
and non porting if you can't figure it out, you would only
be changing one thing in the comparison. Do some trials without
the ports, put in some ports and do some more trials with the
ports. You don't vary anything but the ports, that is what it
is all about. What are all these other variables you are
dreaming up? You do all trials with the same gun and ammunition,
you don't change them in between. The tempurature and atmospheric
pressure may change in the few minutes that it takes to put in
the ports, but not enough to worry about.

And last how did I measure the 1/3rd? Its pretty simple I'll
give you an example. Lets say I measured a muzzle rise of
3 inches without ports by averaging 5 shots fired. Next I
put in the ports and measure 5 shots with the ports and
average the results. Lets say that with the ports the muzzle
rise was 2 inches. You subtract the 2 from 3 and it gives
1. You compare the difference 1 to the original muzzzle rise
and you see that it equates to 1/3. That is how I made the
calculations.

Quote:
Furthermore, how do people who get their gun ported come on this
BBS and say it was a waste of money? I would think that "1/3rd"
would be an unmistakable reduction in rise or recoil.


They say it is a waste by what it cost and how it behaved
before and after. Maybe their gun did not have much muzzle
rise to begin with. If the gun only had about 1 inch of
muzzle rise, and it was reduced by 1/3 then it would be
reduced by 1/3 inch, and this is at the muzzle. If you
look at the stock rise near the cheek, then this rise
would not even be 1/10 inch. Also stock design has a lot
to do with how muzzle rise and recoil feel. A conventional
stock stock fires into your check from the gun going
backwards during recoil, and this is further amplified
if the gun stock is rising during recoil. A parallel
comb does not fire into the cheek as a result of the
gun backing up but gets all its cheek impact from the
stock moving upward. Beyond that you can make the comb
of your stock actually go down hill, that is, the comb
has more drop at the front of comb than it does at the
back of the comb. I usually make my stocks this way. These
stocks really handle recoil well, because as the stock
moves backward, more clearance is available between cheek
and stock and with these stocks all cheek contact come
from gun rise. A gun that is quite barrel heavy has less
muzzle rise than one with light barrel. So a typical
barrel heavy over/under will have less muzzle rise than
an Ithaca model 37 which has considerable muzzle rise.
As I said, if your muzzle rise is small a reduction of
1/3 will be small. Actually I do not put porting on
the guns I build today, because the muzzle rise is so
small on them, that a 1/3 reduction is not very much.
If your muzzle rise is large then a reduction of 1/3
is more important. Still if it is large there are usually
other problems going on also, like a stock with a lot
of drop or a stock with incorrect pitch that places too
much pressure on the toe area of the stock and not enough
contact with the heel area of the stock. These are
factors also in muzzle rise. They don't change the fact
though that muzzle rise is reduced with ports, providing
of course that the ports face upward.


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 Post subject: re: Porting and muzzle jump
PostPosted: Fri Feb 29, 2008 10:25 am 
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And how did you measure muzzle rise?


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 Post subject: re: Porting and muzzle jump
PostPosted: Fri Feb 29, 2008 10:27 am 
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Location: Las Vegas, Nevada
ShootingStar, when you say:
Quote:
You might find it hard to take, but despite what you might think,
your's is not the definitive, final word on porting.


I agree with you insofar as ALL the ramifications of porting go,
but in the context of the subject of this thread, that being, does
porting reduce muzzle rise, my experiment is quite final.
It established beyond doubt through actual trial that it does
reduce muzzle rise, end of story. For the those other items
you mention, about porting and people being mislead about
its recoil reduction etc, you are quite right. To go even
further, I believe the way porting is put in is not the best
way. If porting is done the way I believe it should be done
then it does not increase noise but actually decreases it.
This is something most people will find hard to believe but
it is also something that is fact.


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 Post subject: Re: re: Porting and muzzle jump
PostPosted: Fri Feb 29, 2008 11:09 am 
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Frank Lopez wrote:
...for the most part, muzzle jump, or at least the greatest portion of it, occurs after the shot has left the barrel.


True; and that part which occurs before the shot has left is affected by several factors including barrel weight, c of g, moment of inertia, gunfit, mount, type of pad, shell characteristics and probably other things. POI is also affected by these same factors and the reason why I never do POI testing is because it only works for one shell and at one distance, whether the gun is ported or not.

Does porting reduce muzzle jump? Perhaps, but why does muzzle jump matter? IMO 2nd target acquisition improvement is a marketing ploy because I've never been aware of muzzle jump as a problem when firing off 2 shots in quick succession.

Perhaps the best question is: Does porting improve your scores?

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 Post subject: re: Porting and muzzle jump
PostPosted: Fri Feb 29, 2008 11:25 am 
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How did I measure muzzle rise?

At last an intelligent comment on my post. Before
anyone goes off about it being wrong they really
should understand what I did and so here is what
I did.

I built a cradle out of wood to hold the shotgun.
It was mostly built from 2X4s. It had a section
where the stock butted up against a piece of wood
similar to how the stock butts up against your
shoulder. This is important because the stock
has to be where the recoil is applied. If you
hung your gun from a clothes line, the recoil
would be applied where the string connected to
the gun and if this were in line with the bore
line of the gun then all recoil would be in line
with bore line of the gun and no muzzle rise
would occur, as all recoil would be straight back.
You get muzzle rise because the stock is offset
from the bore line by a small amount and when
the gun tries to go straight back it pivots on
this anchor point which is the muzzle rise.
So I had a piece of the cradle where the stock
butted up against to take the recoil. I could
move this piece up or down if I wished, making
for lots of drop at the pivot point or smaller
amounts of drop at the pivot point. Generally
I just left it such, that the pivot point was
about the same as heel of the stock. Next I
had a guide at the front part of the gun, about
even with the forearm that had a post on each
side of the barrel, so that the barrel could
move upward between these two guide posts, if
the force of recoil was sufficient to move it up.
To measure the amount of rise, I tied a piece of
string to the barrel and it was hangin below the
barrel, and it was drawn through a piece of card
board, which had a slit cut into it. When you
set up for the shot you could measure how long
the string was from barrel to the slit in the
card board. When you fired the gun with a cord
on the trigger, the barrel rising would pull the
string which was pulled through the slit in the
cardboard. The friction of the cardboard held the
string in its position at the point of maximum
elevation of the barrel. So after the shot the
string was not tight between barrel and cardboard
slit. It had all the string that had been used
during upward movement of the barrel during the
shot. By measuring the string after the shot
and comparing it to the length of the string
before the shot you had the figure for exactly how
much the gun moved up at the string attachment
point during the shot. Doing this several
times you could see that it was pretty consistent
with each shot, and taking the average of all
the shots you got a very accurate measure of
just what the barrel rise should be. Next I
put in some ports and tried it, again making
several trials and I had a measure of barrel
rise after the porting. I would start out
with one port on each side of the rib pointed
upward and measure. Next I would add another
pair of ports, and measure. Then add another
port pair and measure. This way I could get an
idea of how many ports did what. I also
varied the size of ports from just under an
1/8 inch up to about a 1/4 inch. I also
tried slots on the top of barrel instead of
ports. I did all this with the ports starting
behind the choke area and I would leave about 1/2
inch to 1 inch between the port pairs. What I
found was pretty surprising. It really did
not matter much how many port pairs you put
in. The first pair of ports pretty much did
the trick. Adding port pairs after the initial
ones did not do very much more. The big difference
was between having none or a couple.

I did this experiment over and over. In those
days there was only a couple guns available
with interchangeable choke tubes. I modified
lots of guns by adding a sleeve to the barrel
that was machined to accept Winchoke tubes.
When I started with a long gun there would be
quite a bit of barrel that I had to remove.
If it had a thirty inch barrel I might cut off
6 inches. Then I added a sleeve that added
a couple inches to the barrel and I would end
up with about a 26 inch barrel. It was with
these barrels that I was cutting off that I
did the experiments. Since I was throwing
away the cut off section anyway this allowed
me to do experiments without screwing up a gun.
If I had not been doing this modification I
would never have performed the experiments,
not wanting to throw money away butchering
barrels experimenting. In those days also
you never did see porting on a shotgun. When
I finally did port one for real use, it was
quite a curiosity. Anyone at the range seeing
this gun with holes in the barrel would ask
about it. I still have the gun and it is
a great shooter. It does not have any more
noise than an unported gun. It has only 3
port pairs per barrel and these are separated
by about 3/4 inch each. You only get the
noise level going up if you put in lots of
ports that are very closely spaced just like
all the factory ones. With a great many
ports spaced very close they reinforce each
other, just like a gang of speakers that
you see in theaters. Just as the gang of
closely spaced speakers really reinforce
each other and carry the sound wave over
a large more powerful area, the port pattern
on factory shotguns, carry the sound wave
over a large more powerful area and give
a louder noise to the shooter.


Last edited by DevilsAdvocate on Fri Feb 29, 2008 11:30 am, edited 1 time in total.

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 Post subject: Re: re: Porting and muzzle jump
PostPosted: Fri Feb 29, 2008 11:29 am 
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Joined: Thu Jan 25, 2007 9:11 am
Posts: 1070
Trickster wrote:

Perhaps the best question is: Does porting improve your scores?

In my opinion.......YES! (Nothing wrong with that, right?)


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 Post subject: Re: re: Porting and muzzle jump
PostPosted: Fri Feb 29, 2008 12:53 pm 
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Joined: Sat Feb 26, 2005 8:52 am
Posts: 859
Location: UK
mike modelle wrote:
I am in complete agreement with Shooting Star. A properly fit gun yields no vertical muzzle motion for porting to cure.



I am in complete agreement with you whilst firing BLANKS :lol: .
Its difficult knowing whether some posts are meant to be funny.
Not meaning to annoy you but good gunfit won`t overcome basic physics. I don`t know about strings (its immaterial anyway) but in folks hands, the gun moves, some of this movement is upwards.


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 Post subject: re: Porting and muzzle jump
PostPosted: Fri Feb 29, 2008 1:55 pm 
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Quote:
At last an intelligent comment on my post.


So your wood frame / cardboard box / string test is now the definitive word on porting? You really think that its margin of error is within enough control to measure 2" vs. 3"? Way too unscientific for me. It seems that most of these responders to this small poll feel the same way.

I have never argued that there isn't a theoretical reduction. My argument is, however, that no human being can notice it, just like the reduction in muzzle jump afforded by a fly sitting on the end of your barrel. Your claim of 33.33% less muzzle jump would be unmistakable to anyone shooting it.

having shot both types quite a bit myself i would have to agree with the responders to this poll and the Technoid:

Quote:
Porting: A few new guns, notably a large part of the Japanese
Browning Citori series and many of the Berettas, now come with barrel
porting standard. There are also a dozen aftermarket companies that
perform this modification. Does it actually work? Probably a little, but
equally probably, not enough to matter. It definitely does not work as
well as it does in the high gas pressure environments of rifle and
pistol. Stroboscopic photography seems to show that porting does indeed
slightly reduce muzzle jump when the gun is unrestrained. The heavier
the shell, the better it works. Whether the reduction in muzzle jump
will be noticeable to the shooter is another question, especially if the
shooter uses light loads.

In the 1970s the Technoid conducted a blind comparison (some say that
all of the Technoid's comparisons are blind) of Magnaported barrels vs
standard barrels on a Remington 1100 and could detect absolutely no
difference. Then again, it is hard to tell with gas guns. His later
tests on two identical Browning Citori GTI O/Us, one factory ported and
one not, also showed no discernable difference. We are talking about
muzzle jump here. No one has ever substantiated any claim that porting
has reduced rearward recoil, although several of the machine shops claim
it. Be aware that many types of porting increase muzzle blast to
obnoxious levels, but other port hole shapes do not seem to.


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 Post subject: re: Porting and muzzle jump
PostPosted: Fri Feb 29, 2008 2:30 pm 
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Quote:
So your wood frame / cardboard box / string test is now the definitive word on porting?

Correct, the test consistently showed a reduction in muzzle rise
with porting, and it did it without exception. Also I did not use a
cardboard box. This is your inability to read and understand
showing again. I used a piece of cardboard at a specific point
because it was a cheap and easy way to measure how much
a string moved. I used a string because it was a cheap and
easy way to make a measurement. The materials were crude
but since they show consistent results there is no need to replace
the wood with titanium, and the string with a stainless steel
plunger, and the cardboard with an adjustable friction piece
with somesort of adjustable tension on it. Also I did this test
quite a few times. If it were going to give inconsistent results
in had many opportunities.

Quote:
You really think that its margin of error is within enough control to measure 2" vs. 3"?

Yes, but remember the 2" and 3" were just an example of how I made
the calculations. The actual calculations may have been 4.1 versus
6.2 inches and the notes are long gone. You are grasping for straws
trying to make an argument. In fact as I made the tests I got very
consistent results. When I made numerous trials like making 5 shots
instead of one shot, by the time I got the the 4th of 5th shot I could
easily predict the outcome because the first 3 had been so consistently
together.

Quote:
Way too unscientific for me. It seems that most of these responders to this small poll feel the same way.

Yes apparently it is.

Quote:
Your claim of 33.33% less muzzle jump would be unmistakable to anyone shooting it.

Pray tell, when did I make this claim? Actually I gave specific
information that if your muzzle rise was small then a reduction
of 1/3 would also be small. Don't imagine I said something and
then argue against what you imagine I said, just stick to what
I said and you should be alright.

Quote:
having shot both types quite a bit myself i would have to agree with the responders to this poll and the Technoid:

As far as I know Bruce Buck, the Technoid has never made any
actual tests on muzzle rise and porting and if he did I am quite
certain his results would show a decrease in muzzle rise. I know
he is not a big fan of porting and actually neither am I, but facts
are facts and opinions especially ignorant opinions with no tests
made are not as reliable as actual tests. You can agree with
ignorant opinions all you want, but it makes more sense to
rely on actual test results. That is why I did the tests. I wanted
real information not just my guess as to what was happening.


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 Post subject: re: Porting and muzzle jump
PostPosted: Fri Feb 29, 2008 2:39 pm 
As a retired pilot I am well aware of the effects of off-centerline thrust. Every time a shotgun fires that is not mass-aligned with the thrust vector it acts the same as a jet with an engine out: It has flip if the mass center and the force applied to the system are not the same. For long guns proper fitment - how you engage the system -remains paramount and key to overcoming it.

In handguns the effect of good porting is very evident in custom race guns where the jet effect of exhausting gases with a reward and upward impulse vector speed recovery on the rapid fire stuff that discipline requires. The principal extends to shotguns of course since it's physics.

Personally, in my discipline I avoid all physics issues by use of the 20 in 12 events thru a well-weighted weapon and crawling into the gun so that when it goes off the motion is straight back and I enjoy the fruits of still having a gun pointing where I am looking during and immediately after the loudness part.


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 Post subject: Re: re: Porting and muzzle jump
PostPosted: Fri Feb 29, 2008 2:39 pm 
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ryansmith wrote:
Rastoff wrote:
Wiseass?

OK, but the original post specifically said that he wanted to hear how porting affected muzzle jump not recoil.

You are correct to say that recoil is a function of Newton's third law. However, in relation to porting it has more to do with muzzle jump. You see the ports are angled upward. The gas goes up therefore forcing the barrel down and counteracting muzzle jump to some degree. Therefore, in accordance with Newton's third law, porting has to have some affect even if it's small.

Some say that porting has no affect. That's why I mentioned Newton's law of reciprocal actions.

Muzzle flip is also a function of recoil and the angle of the stock. I only addressed the action of the porting and didn't go into the cause of muzzle flip.


Sure there is some theoretical reduction in flip. But if a fly is sitting on the end of your barrel when you pull the trigger then theoretically muzzle jump is also reduced. :lol:

In a shotgun, with relatively low pressures, I contend that there isn't a human being alive that is sensitive enough to notice the difference.

Not that anyone cares, but I'm going to have to agree with Ryan on this one. If there is a difference, it's imperceivable on the part of any human being.

I also believe that those who seriously promote porting simply think those little holes look cool and need some reason to explain the rationale behind having them in their barrels since admitting that the "coolness" factor played a part would be a bit uncomfortable.

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 Post subject: re: Porting and muzzle jump
PostPosted: Fri Feb 29, 2008 2:52 pm 
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Quote:
but facts
are facts and opinions especially ignorant opinions with no tests
made are not as reliable as actual tests. You can agree with
ignorant opinions all you want, but it makes more sense to
rely on actual test results. That is why I did the tests. I wanted
real information not just my guess as to what was happening.


you do realize that just because you did a test in your own little lab that it is not a definitive, scientific proof, correct? That's all I'm saying...and I think that's all ShootingStar is saying. You're acting as if "barrel porting" = "1/3 reduction in "muzzle jump" is the same thing as F=MA :roll: .

The definition of muzzle porting is variable (how many ports, their size, shape, direction, etc), 1/3 reduction is variable (changes based on how the gun fits a particular individual, as you say yourself), and the definition of "muzzle jump" is even something that is not easily quantifiable.

the bottom line is that what is actually going on is FAR FAR too complex to eyeball and measure with some cardboard and wood and string. Let's not kid ourselves here.

And bottom line, whatever IS going on, is too minute to register in our brains or on our shoulders. I promise you that if you did a blind taste test, the results would NOT show a pattern where people could identify which gun was ported and which was not.


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 Post subject: re: Porting and muzzle jump
PostPosted: Fri Feb 29, 2008 5:02 pm 
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Quote:
the bottom line is that what is actually going on is FAR FAR too complex to eyeball and measure with some cardboard and wood and string. Let's not kid ourselves here.


You never give up do you? It is not complex. It is simple as he11.
Distance is distance whether you measure it on a string or on a
gold plated scale. What is important is the accuracy of the measurement.
If you are not able to measure a 4 inch string and get 4 inches every
time then you have quite a problem. I don't have that problem.
Also you are the one saying that I use "eyeball" for my measure
Where did you come up with that? You really
have to stop making this stuff up. I did not eyeball it. I used
great care and measured the string with a very good scale. The
fact that I used card board as the medium for which the string
was pulled through also worked very well. Before you pick on
this why don't you run an actual test? Cut a slit in a card board
and pull a string through the slit. Observe first hand if the string
stops going through when you stop pulling or if it just keeps
right on going and out the front door. I think you will find it very
easy to fashion a piece of card board and pull a string through
it. Even an idiot should be able to do that, not saying that you
are an idiot, but just pointing out that this is simple not complex.
After you cut a slit in cardboard and pull a string through it, next
try measuring the string. See if you can do that without poking yourself
in the eye or falling down. I think that you will find this operation
to be easy, again something even an idiot could do. See if
you can measure the distance 2 or 3 times and get the same
result. After you have tried all this, I believe you willl see just
how simple this is. I don't believe that you will have trouble getting
the same reading every time you measure the string. If one time
you measure it and get 1 1/2 inches and next time you get
7 and 1/2 inches then quit the experiment as it is just too
complex for you. Your only argument against this is the test done
by Bruce Buck where shooters made a blind comparison on
recoil and if they could tell the difference. That test did not
even attempt to measure muzzle rise. I am quite familar
with that test and it had no data on muzzle rise. Are we
exceeding your attention span here? Maybe you really can't
measure a string, but I have faith in you. Try real hard and
you can do this. If you don't believe me write off a letter to
the technoid and ask him if he believes it is possible to measure
how long a string is using nothing more than an ordinary
ruler, or if this is way too complex for mortals.
I know Bruce and I am sure he could handle this and I also
believe you can.


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 Post subject: re: Porting and muzzle jump
PostPosted: Sun Mar 02, 2008 9:27 am 
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I shot 250 rounds with my unported gun today :D . I made a point of looking at the muzzles of various ported guns and they sure do flip less. I knew this already of course since I have had a ported 682 before. I`ll take a bet with anyone who thinks its too imperceptible to be detected by the human eye. You don`t even have to be holding the gun to know.


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 Post subject: re: Porting and muzzle jump
PostPosted: Sun Mar 02, 2008 12:01 pm 
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Another thing I want to emphasize is that a ported
gun does not have to be louder. Most factory port
jobs though seem to be very loud. The reason they
are loud is because they use very many holes spaced
very close together. These closely spaced holes
give a very large sound wave, instead of one small
one that you would get if you only had one small
hole. The holes being spaced very close together is
the problem when it comes to noise. Each added hole
just makes the sound wave larger and this increases
the power of the sound wave and therefore is much
louder when it reaches your ear. If you notice
speakers in movie theaters they also group a whole
gang of speakers side by side to get good powerful
large sound wave output. If they put those speaker
over a larger area with large distance between them
the output sound wave would not be as powerful.

At one point I was working on an old car and it needed
an exhaust system. I thought you could make the
system without a muffler and still make it quiet
by using a pipe with holes in it and I tried it.
I ran a straight pipe from the header pipe all
the way back to the rear bumper where it did a
90 degree turn and then the pipe ran along near the
bottom of the bumper to the other side of car. I
welded a piece over the end of the pipe so that
there was no opening. Then I drilled a bunch of
1/8 inch holes in this section of pipe that went
across the rear of the car. I made at least an
inch between the holes so that each small sound
wave would die without adding to the strength
of the one beside it. I drilled enough holes so
that I achieved an area equal to about double
what the area that was at the end of the pipe where
I had welded a plug onto it. I figured this would
let all the gas out with very little back pressure
since the exit holes had such a large area, and
yet each exit holes would only put out a small
sound and would not add to the others. It worked
and worked well. The system was very quiet and
had just as good power as it had before with
a straight thru muffler that had been loud.

The guns I ported with just a few ports did not
have any extra noise that anyone noticed and I
wondered if the holes actually made the gun
quieter like the holes in my exhaust system above.
I had a junk barrel at the time so I decided
to experiment and see if ports actually could
make a shotgun quieter. To do the experiment
I made a number of tests where I asked many
people which barrel was quieter. I fired two
guns one after the other and quite a few
witnessed that my experimental barrel was
louder than the other. The experimental barrel
was on an Ithaca M37 was about 26 inches and
the other gun was a Remington with a longer
barrel. AS expected everyone choose the
shorter barrel as louder. Next I drilled
umpteen jillion holes into the barrel with
an 1/8 inch drill. I left at least an inch
in between them and some exited up, some to
the side, some down. Next I fired the two
barrels one after another and asked quite
few which one was louder. They all choose
the opposite barrel this time. So adding
ports did make the gun quieter. I am not
the only one who figured out that ports can
make a gun quieter. Several people have figured
it out. Here is one of them:

http://www.gunandgame.com/forums/shotgu ... t-gun.html

Now after all this you have to wonder why manufacturers
and pros that put those ports into barrels all do it
in such a way to make the guns louder. If they did
it right, the guns would have actually been quieter.

After all this don't get the wrong idea. I am not
in the business of porting guns. The only ones I
have ever done are my own guns and I don't work
on anyone else's guns, so don't even ask me to do
this. Some people have asked me to do work at times
like this after observing mine, but gunsmithing is
not my business and I don't work on other peoples
guns. If someone does want to port their guns, I
don't really advise it. There are a number of other
things you can do to help the gun in the recoil area
and I would recommend those things. If someone
does want to port any of his own guns, I can give you
information on how to do it without screwing the
job up, but as I said, I don't really recommend it.
I certainly don't recommend a factory gun with porting
and refuse to buy any gun ported that way with those
noise levels.


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 Post subject: re: Porting and muzzle jump
PostPosted: Sun Mar 02, 2008 3:41 pm 
Diamond Grade

Joined: Thu Jan 25, 2007 9:11 am
Posts: 1070
OK; side question: do you hear a difference with Benelli's porting? I don't think my Supersport (with someone else shooting) sounds as loud as other ported guns and no one has ever mentioned that it is loud. (Totally anecdotal and non-scientific.)


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 Post subject: re: Porting and muzzle jump
PostPosted: Sun Mar 02, 2008 4:22 pm 
Crown Grade

Joined: Tue Jan 09, 2007 5:35 pm
Posts: 2205
Location: Las Vegas, Nevada
I am not that familiar with Benelli's porting pattern, but I
notice a big difference in the number and density of ports
on some patterns. I can remember seeing some Mossberg
patterns with a lot fewer ports than what you see on
most over/unders.

The best way to judge your noise level is to just fire
the gun with the same ammunition with a gun that
is not ported. Hold one in your left hand and one in
the right hand. Fire one then the other. You will
be able to judge any difference in noise level, even
with ear protection on. You might try it twice. Alternate
which one you fire first. That way any difference in
your perception by whichever comes first will be
eliminated. You can also have a couple others stand
close by and get their judgment also.


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 Post subject: re: Porting and muzzle jump
PostPosted: Mon Mar 03, 2008 8:20 am 
Field Grade

Joined: Thu Nov 30, 2006 9:09 am
Posts: 55
I'm one of the almost 70% that don't notice any muzzle flip reduction.

No doubt, it does reduce muzzle flip, but too many variables that "cause" muzzle flip for individuals, i.e. stock fit, ammo, balance, stance, etc. Plus, shotgun ammo is low pressure.

No purpose shooting singles of course. On doubles, often you have to change direction with the gun anyway, so slight reduction in muzzle jump isn't going to be noticed by many...IMHO. I don't even notice it shooting two shots at a single target. But I'm not "looking" for it since everything happens quickly, stock fits, balance correct, etc, etc.

If you want to notice it...maybe you can. That's on the level of forcing cone modifications, back boring, reducing recoil and all that!

Perhaps, with short barrels, heavy loads and shooting at static targets, like paper bullseyes/steel targets, etc, porting may be of some value for quick follow up shots....that's "rifle" shooting with a shotgun anyway.

They are louder, however, and allow "crap" to ooze out when you clean the barrel...that's great :D


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 Post subject: re: Porting and muzzle jump
PostPosted: Mon Mar 03, 2008 11:15 am 
Crown Grade

Joined: Tue Jan 09, 2007 5:35 pm
Posts: 2205
Location: Las Vegas, Nevada
It is without doubt true that many don't notice any
muzzle rise. But, also true that many of those that
don't notice it, can notice it if they try. The basic
experiment where you shoot an over/under while paying
attention can demonstrate this. Take a standard over/under
and load both barrels. Put the gun to your face in
normal firing position. Close your eyes and fire one
barrel after the other, with time enough to reset the
gun to position. Do this firing the bottom barrel first
and then do it firing the top barrel first. Most
people will notice that the bottom barrel apparently
shoots into the cheek, less than the upper barrel. This
is because the top barrel gives more barrel rise. This
is most noticeable on light guns with normal field stocks.
It is less noticeable as the gun gets heavier, especially
barrel heavy guns and with a parallel comb. Also, the
unsingles that came onto the trap market some years back, was
because of this fact of lower barrel giving less muzzle rise.
Also about that time extra high ribs came into vogue. Ribs
like what Simmons called olympic ribs. The sole purpose
of these high ribs was to reduce muzzle rise by being
able to use about an inch less drop at the heel of the
stock, and compensating for this straighter stock by
raising the rib. Even though a person might not notice
the muzzle rise, it can still be a factor, long term
in shooters developing a flinch, especially of the
kind where the shooter pulls the gun down with the
forehand while pulling the trigger. Most shooters
will do this and it is entirely subconscious. This is
apparent when a person has a missfire and the gun
does not go off. Most shooters will be seen pulling
the gun down at this time, with this flinch which is
never seen during a normal shot. So many people who
are unaware of it have developed a counter measure to
muzzle rise even if they don't know it.


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 Post subject: Re: re: Porting and muzzle jump
PostPosted: Mon Mar 03, 2008 7:42 pm 
Crown Grade
User avatar

Joined: Sun Jun 26, 2005 4:43 pm
Posts: 2325
Location: PA Dutch Country
Rastoff wrote:
wwb,
I'm no physics major. I can quote Newton's laws and I understand what they mean. I even know what harmonics are and I understand how they are created. But, applying the actual math is a little above me.

Are you saying that a shotgun barrel is more "stiff" than a rifle barrel? I would think it's the other way around due to the wall thickness to bore ratio. From what I can see when I look at my Ruger 10/22 and my Beretta 303, the 10/22 seems to have a higher ratio of bore to wall thickness than the 303. Wouldn't that mean the rifle has a stiffer barrel?

Also, could the harmonics be caliber and load related?

I hope this comes out as I intend. I'm really interested in this. I'm always interested in scientific thinking.


The major factor in stiffness is mass in the OD, not the overall mass. That and shorter length. The relative stiffness of your 12 ga. barrel is going to be a higher than your .22 barrel. Archery is one place stiffness is really important. The thickness of the (aluminum) shaft affects stiffness to some extent but is varied for weight mostly, the OD is the most important variable in stiffness, along with the arrow length. Different types of bows and different releases change the stiffness required.

Stiffness is varied in rifles by barrel thickness, fluting, and the bedding/floating.

I don't believe that harmonics has much to do with shotgun patterns...I think the Benelli Crio barrels are a joke. With rifle, harmonics absolutely matter. That said, I have read reports "on the net"..one was of steel shot patterning great from a standard weight 1187 but poorly from an 1187 Light Contour with same barrel length, exact same choke, and same box of shells. The shooter's theory was that the stiffness was the difference. I'm not so sure, but..?

Jeremiah

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