[code5coupe]

When measuring with an industry-standard (SAAMI) chronograph, a full choke reports slower speed than it would report shooting the same shells through a cylinder choke.
..... it seems unlikely anyone would notice anything based on choke constriction.

Neil's first sentence states the opposite of anecdotal indications posted elsewhere in this thread. Who is closer to the truth? .....I don't know. Probably Neil.
Neil's last sentence is likely VERY close to truth, since even a 50 fps delta at the muzzle would equate to about 15 fps at the target.
Even if the increased constriction of a tighter choke DID increase back pressure, it could only do that by slowing the shot charge down (or, at best, reducing acceleration) just before exiting the muzzle. How can slowing something down speed it up??

 

[Velvet Ears]

When shooting a specific load, there are 2 constants. Velocity of the shell and gravity. When switching chokes you introduce the variable of friction. The tighter the space you have to fit the shot, the more friction is generated. So, if anything a full choke actually slows down the velocity due to more friction at the constriction point.

With this being said, if you have a tailwind it will definitely speed up a full choke more than the others. This is due more wind surface area created by the tighter pattern.

 

[SpringerFan]

I disagree!
It is not necessarily more resistance as more back pressure.
I have measured speed between chokes and there is a difference.
Think of a garden hose with your thumb of the end. Increased pressure = faster water.
mike

You have not created any more new pressure by placing your thumb over the end of a hose. You have just restricted the flow which makes it feel like more pressure. So now the same pressure acts on a smaller volume of water. That makes it able to go faster & farther. So this is a bad analogy to the shotgun example where you are not reducing the weight of the shot.

Restricting the bore of a shotgun will not create any new energy or pressure. You get the same amount of pressure acting on the weight of the shot charge.

Acceleration = Force / Mass. You get the same acceleration unless you increase force or decrease mass. You can’t increase force by restriction. If you did, you would be creating energy which isn’t possible.

 

[code5coupe]

With this being said, if you have a tailwind it will definitely speed up a full choke more than the others. This is due more wind surface area created by the tighter pattern.

A. The wind does not push the shot charge, like a sailboat. In most of our situations, the load is traveling FASTER than the tailwind.....

B. Frontal area remains the same. Air resistance acts on individual pellets, not on the "pattern area". Doesn't matter how far each pellet is separated from its neighbor, its air resistance is the same.

C. Using your logic, the tighter pattern would have MORE drag (air resistance) than the more open pattern. Off course, it doesn't.

 

[rw993]

If you twist the nozzle on a fire hose the water moves faster and travels farther.
Henry

You have a constant flow of water in a fire hose. The shot is a one time push. Apples and Artichokes

 

[Velvet Ears]

The wind does not push the shot charge, like a sailboat. In most of our situations, the load is traveling FASTER than the tailwind.....

Frontal area remains the same. Air resistance acts on individual pellets, not on the "pattern area". Doesn't matter how far each pellet is separated from its neighbor, its air resistance is the same.

Using your logic, the tighter pattern would have MORE drag (air resistance) than the more open pattern. Off course, it doesn't.

You make a very valid point

 

[paul Harm]

I don't believe you could tell the difference in 50fps. In skeet with 90 degree crossers there's only a couple of inches of difference in lead. With a 24 to 30" pattern and going away birds as in trap the lead difference might be a inch. It broke the bird quicker ? How much quicker ? Does it really make a difference if it broke the bird a foot quicker ? The faster shot starts out, the quicker it slows down. Just how good do you have to be to do a blind test and tell the difference. I just let a friend who is a 27yd shooter shoot my Parker SBT. I gave him some of my 3/4oz shells going 1170fps. After four shots he said, " man, do those ever smoke the bird, but it's like shooting a BB gun - no recoil ". He never commented on how fast the bird was broken. Now you 27yd shooters would probably know the difference in a 1100 and 1275 shell when shooting back at the 27.

 

[arnold55]

Increased pressure equals increased velocity!
Review the shape of rifle cartridges...
and yes I am taking into account of the powder....
mike

 

[reyper]

Believe what you want just don't think about it right before calling for the bird! Good shooting, Rey

 

[digodell]

You have not created any more new pressure by placing your thumb over the end of a hose. You have just restricted the flow which makes it feel like more pressure. So now the same pressure acts on a smaller volume of water. That makes it able to go faster & farther. So this is a bad analogy to the shotgun example where you are not reducing the weight of the shot.

Restricting the bore of a shotgun will not create any new energy or pressure. You get the same amount of pressure acting on the weight of the shot charge.

Acceleration = Force / Mass. You get the same acceleration unless you increase force or decrease mass. You can’t increase force by restriction. If you did, you would be creating energy which isn’t possible.

Very well said, a lighter load same charge weight will travel slightly faster.

 

[arnold55]

We know that a full choke will shoot a higher pattern % at greater distances than a more open choke.
My instincts tell me that the shot string of a full reaches the target more quickly than a more open choke.
What do you think?
What do you know?
Henry

"YES"
Also...if you have the time you may want to read "ShotGunning-The Art and Science" by Bob Brister
mike

 

[flashmax]

Increased pressure equals increased velocity!
Review the shape of rifle cartridges...
and yes I am taking into account of the powder....
mike

No. It doesn't. Nowhere in shotgun velocity measurements does pressure play a part. Look at reloading charts. There are many, many, MANY loads with maximum sammi allowable pressures that deliver lower velocity than other loading of the same payload weight.

 

[code5coupe]

My instincts tell me that the shot string of a full reaches the target more quickly than a more open choke.

Why might that be?
If the velocity of the individual pellets are identical, why would their collective velocity be greater?

 

[Ram Rod]

I appreciate the debate .
Neil Winston answered the question to my satisfaction.
Thank you All!!!!
Henry

 

[Neil Winston]

Based on my laboratory tests here:

Chronographing Shotguns

and here:

http://www.claytargettesting.com/study2/Study2.2.pdf


which cover at least 10,000 shells over 20 years with two models of inductive (SAMMI specified) chronographs and many home hobbyist brands, you should accept the speed difference between cylinder and full choke reported speeds for the same shells the two types of chronograph I cite, about 25-35 fps, and ignore the uninformed guesses - and worse yet their "explanations" - of others typing here who have neither seen nor touched an inductive chronograph and have how idea whatever how they work.

Recall, however that the inductive chronographs reported slower speeds when shooting full chokes in place of cylinder chokes;light operated chronographs reported slower speeds when shooting cylinder chokes in place of full chokes.

 

[DennyK]

I’m mystified as to why people would get so wrapped up in this when they should be focusing on the important stuff like 7-1/2s vs 8s.

 

[Perazzi_MX8]

This thread has more bullshit in it than a turkey on the Thanksgiving table. The water hose analogy is so removed from shotgun shell velocity it’s hysterical. This is like 2 drunk retards trying to solve the worlds problems. If you feed a shit eating dog faster does he run faster?

 

[arnold55]

Guide to shotgun choke. Everything you need to know.
Read more at Guide to shotgun choke. Everything you need to know.
Shotgun ballistics are much more complex than one might think because there are so many variables: atmospheric conditions; shot size; shot density; shot coating; wad, primer, powder and case type; barrel diameter (a nominal 12 might be anything from .710 to .740 in internal diameter) and internal geometric form; barrel steel and wall thickness; and, not least, the length and form of the choke constrictions themselves. Some chokes are short, others long. Some are simple conic constrictions, others have a cone that leads into a parallel section, yet others have complex forms, including features such as radiused walls, relieved sections or expansion chambers.

While we are getting technical, let me note that tight shotgun choke increase pressures, and hence velocity. A point of choke is worth about 1ft per second on velocity.


Read more at Guide to shotgun choke. Everything you need to know.

Shotgun Choke and Shot Pattern
When a shotshell is fired from a shotgun, the pellets leave the barrel and begin to spread or scatter. The farther the pellets travel, the greater the spread of shot. Shotgun barrels have a choke to control the spread or shot pattern.

The choke of a shotgun acts like the nozzle of a garden hose. As the nozzle is tightened, water shoots out in a long, narrow stream, similar to the full choke on a shotgun. As the nozzle is opened, similar to the cylinder choke on a shotgun, water shoots out in a wider spray.

 

[AusAmateur]

 

[flashmax]

Guide to shotgun choke. Everything you need to know.
Read more at Guide to shotgun choke. Everything you need to know.
Shotgun ballistics are much more complex than one might think because there are so many variables: atmospheric conditions; shot size; shot density; shot coating; wad, primer, powder and case type; barrel diameter (a nominal 12 might be anything from .710 to .740 in internal diameter) and internal geometric form; barrel steel and wall thickness; and, not least, the length and form of the choke constrictions themselves. Some chokes are short, others long. Some are simple conic constrictions, others have a cone that leads into a parallel section, yet others have complex forms, including features such as radiused walls, relieved sections or expansion chambers.

While we are getting technical, let me note that tight shotgun choke increase pressures, and hence velocity. A point of choke is worth about 1ft per second on velocity.


Read more at Guide to shotgun choke. Everything you need to know.

Shotgun Choke and Shot Pattern
When a shotshell is fired from a shotgun, the pellets leave the barrel and begin to spread or scatter. The farther the pellets travel, the greater the spread of shot. Shotgun barrels have a choke to control the spread or shot pattern.

The choke of a shotgun acts like the nozzle of a garden hose. As the nozzle is tightened, water shoots out in a long, narrow stream, similar to the full choke on a shotgun. As the nozzle is opened, similar to the cylinder choke on a shotgun, water shoots out in a wider spray.

It ain't what you know. It's what you think you know that ain't so.