No but I reckon it is much like the game bird suggestions on the back of old shotshell boxes....close enough so that one does not overly wonder or worry.

 

That’s a fair point Multiflora. My interest is not to challenge the accuracy of what’s claimed but to learn the history behind the image. As with most things shotguns, the facts were established long ago and hold true today. Personally, I enjoy knowing not only what they found but how they found it.

 

That exact image was in our Hunter Education booklets the students got when I started teaching in 1990.

Steve

 

Oberfell and Thompson, The Mysteries of Shotgun Patterns, Oklahoma State University Press, 1957
Pattern Percentages for All Degrees of Choke for All Distances

Distance in Yards 15 20 25 30 35 40 45 50 55 60
Choke Full.......... 100 100 100 96 82 70 58 48 39 32
Modified............. 100 100 96 83 71 60 49 39 32 26
IC......................... 100 96 83 71 60 50 41 32 26 21
Cylinder................ 98 83 71 59 49 40 33 26 21 17


“Shot Pattern Spread” from Field and Stream Sept 1964.
I do not have the original article but assume the shells were Winchester/Western Mark 5 12g 1 1/8 oz. with the polyethylene shot collar introduced in 1961. Modern loads are likely better.
Yards.……...10……15……20……25……30……35……40
Choke
Full…………. 9……..12……16……21……26……33……40 inches
Mod…………12…….16……20……26……32……38.…46 inches
Imp Cyl…….15…….20……26……32…..38…...44.…51 inches
Cylinder……19……26……32……38……44……51……57 inches

 

Hello All,
In many places I’ve seen the included graphic describing shotgun choke patterns. Does anyone have information on when this information was compiled and the methods/equipment used? Thanks for any help.

View attachment 100647

It is a SWAG and misleading at best. If you actually read about chokes and patterns from sources that have studied the subject of shotgun patterning, you will understand what I am referring to. There is also nothing like doing some patterning yourself with your loads and your shotgun. Anyway......

Bob Brister - Shotgunning the Art and the Science.
Dr. A.C. Jones - Sporting Shotgun Performance

The name of the University escapes me, but back 20-25 years ago a British University ran a study on shotshell patterns using an electronic pattern board, that would count pellet strikes, pellet energy/velocity, time lapse from the first pellet strike until the last and every pellet strike in between (shot string length) and where each pellet hit on the pattern board. (and probably more than that). It was very interesting and backed up what E.D. Lowry found years earlier.

As well as, Major Sir Gerald Burrard, who was one of the first to really study and compile findings. E.D. Lowry who worked for Olin/Winchester, and did many studies of small projectile performance for the DOD. The nice thing about Mr. Lowry was that he had no bias as he wasn't a shooter. If you google names you will find articles by Mr. Lowry. Maj. Burrard also wrote at least one book that I know of. One thing you will find is that most of what we know about shotshell performance was studied and correct conclusions drawn long ago.

Kinda went like this, Maj. Burrard said some stuff and E.D. Lowry confirmed it and added to it. Bob Brister confirmed what Burrard and Lowry said. Dr. A.C. Jones confirmed what they all said. I am an E.D. Lowry fan, mostly because I got to have a couple conversations with him when he was selling and developing his shotshell software. I am also a Dr. Jones fan.

 

Drew, that would be interesting to know if this graphic predates the plastic shot cup.

Dogchaser, I have read both Brister and Jones. Also I am familiar with Burrard and Lowry. Personally, I am inclined to consider Jones’ work the best.

 

The Remington one piece 'Power Piston' polyethylene wad was introduced in 1963 for target loads.

 

Please note that this is SHOT STRING, not pattern density.
The youtube video of shot string shows a heck of a lot about how various shells have different shot strings. It shows conclusively that the shot string is not the same length as the pattern diameter. NOT EVEN CLOSE!
The diagram is baloney.
Fortunately, shot string is of no practical interest to shotgun shooters because it just doesn't matter for any practical ammunition.

If you want to get all physics theory on it...

We know that the shot string at the muzzle is about an inch, the stack height of the lead.

A good model for shotgun pellet speed from 0 to 60 yards is an exponential decay. (You just need to work out the coefficients based on your particular ammunition. This will depend on pellet size and roundness and material density. It may depend on initial velocity, too. Buffeting through the sound barrier could be a minor effect.

Using a high speed camera, we can find the shot string length at 50 yards. This translates into different velocity for the fastest pellet and the slowest pellet.

If the pellets were all perfectly round and the same size and material, the difference in velocity is due to magic. We can use calculus to find the shot string length at various distances. Ick.
We can also notice that the shot string length is roughly half at 25 yards what it is at 50 yards. (Linear approximation)
It's roughly 1/4 as much at 12.5 yards.

Since the shot string doesn't make any practical difference for reasonable ammunition, there you go.

Since the variation in velocity must be due to the physical nature of the early and late pellets, it's simply a statistical variation in the size/shape/density found in the payload. What a mess to calculate now! Make a computer model.

If one happens to be working on military grade anti-drone top-secret shotgun cannons, ya'll are using a heap o' tungsten, can work out the exact computer models based on that ammo, and spend a lot of money to find out that.. shot string still doesn't matter.

 

Hello Stinky,
Please help me understand how your response is relevant to this thread. The original question did not ask or insinuate anything about shot string.

 

title of the illustration: EFFECT OF CHOKE ON SHOT STRING AT VARIOUS DISTANCES
then it says
"Circles represent the diameter of a lead shot string (in inches)..."

We measure pattern density as the percentage of pellets inside a 30" circle at 40 yards.

Maybe this diagram is trying to express something like "If I draw a circle with 97% of the pellets inside, what's the diameter of that circle at various distances?" But that's not what it literally says.

Let's assume that a nice published diagram is about what the title and dimensional explanations say.

 

I was told there would be no math?

 

Physics minor here.


There are entirely too many variables for ANY basic chart to be reliably relevent.


Real quick...

Pellet type (00 Buck, #7 bird)
Pellet composition (lead, tungsten etc)
Pellet weight/density/variances
Pellet conformity (size/shape/deformity)
Pellet number
Wad type
Cup type
Charge/powder type
Choke type variance (ID vs length)
Constriction (not everyones is the same)
Barrel length
Barrel ID (inner diameter)
Barrel composition (chromed vs steel etc)
...Etc.

This chart gives a general idea, its best to pattern your shot with your shotgun and your chokes in the conditions youll be shooting in.

If you want to be scientific about it, take this chart as a guide and see what yours does with X ammo at Y distance with Z choke in A/B/C conditions, take some cellphone shots at whatever temp/pressure/humidity you are at to visually compare and measure, normalize for STP, then compare with other loads or shotguns or chokes or whatever. Rain is another variable like foliage i would leave out.


This will give you a baseline of what to expect with similar loads and/or conditions in a matrix model you can refer to, or get a general idea from.



There is no simple chart that will be accurate for everyone.

 

Physics and more stuff I don't understand

Abandon All Hope of Understanding Shotshell Ballistics

David J. Compton, “An Experimental and Theoretical Investigation of Shot Cloud Ballistics”, 1996
http://discovery.ucl.ac.uk/1382490/1/396689.pdf

 

That might be the study I was referring to, but I can't get the pdf to open.

 

Hello Drew,
Thank you for sharing that link. It will give me some reading material through the weekend.

It seems my request for information about the history of an image we all, seemingly, admit to knowing has sparked a tangential discussion about its validity and the many possible investigations that one might reference to refute it. Interesting points worth further consideration all around…

 

Charlie Brown said it best... "AAUGH!" But he hadn't seen the choke tests that Gil Ash did years ago.
Sorry about all the ads but take your time reading this and actually looking at what the pictures are showing. And also look at what the vast majority of the top shooters have to say... Most will tell that they used to be constant choke changers but now most are shooting Mod or IM and rarely, if ever, change.

https://www.shootingtimes.com/editorial/longgun_reviews_st_headintheclouds_201002/99884

 

The question wasn't physics one rather a history one. Two different departments all together.

 

I must be as dumb as the creator of the chart because I'm not all confused by the title or the sub heading. A "string" has a length. A "string" also has a diameter. A shotstring is not merely the two-dimensional distance between the first and last pellet, it is also three dimensional. The chart makes no attempt to describe the shotstring length, only the shotstring diameter at various yardages with a given choke. Seems perfectly OK to me...not untrustworthy at all.

Maybe if one substitutes "shotcloud" for "shotstring" it will digest a little easier.

Since the chart and term "shotstring" both date from well over 50 years ago, I suspect the term was not mis-used but rather mis-interpreted by some modern day readers.

 

That’s a fair point and perhaps the chart is 50 years old. I think to avoid confusion, shot cloud is a much better term because modern day discussions of shot string revolve heavily around the length of the shot swarm to the point that people debate whether or not shot string matters at all. Well if shot string is being used to refer to pattern spread then of course it could matter a great deal! (Unless you are in the camp that choke doesn’t matter )

 

Mea culpa. I am misinterpreting and jargon changes over time.

 

Find what works for you and use it. Practice putting the pattern you have where it needs to go. On a good day chokes don’t matter, on a bad day chokes don’t help. Don’t fall into the trap of wondering how many angels can dance on the head of a pin.

 

Well, this subject has all been hammered to death over the last 100 years.
Shells, powder, wads, speed, mid bore size, fix chokes or mobile chokes, all really do have a profound effect on shot patterns.
You just cannot compare a tight mid bore barrel, hand installed fixed chokes, Celotex fiber wad, 20th century data with a back bored barrel, plastic wad, 21st century powder, and screw in chokes. The patterning results are from two completely different worlds.
Whatever shotgun you are holding, new or old, fixed choke or mobile, new powder or old, go to the pattern board and learn, but don't depend on data that is out of date and out of context and does not apply to your gun.
Mike
It's like comparing an 1800s muzzle loader to a modern Blaser.

 

More like 150 years

There were several gun trials in London in the 1870s and "Full" or "Choke Bore" was (eventually) established as the choke constriction (with various profiles and 'swaged' choke from the outside) that placed 70% of the shot charge in a 30" circle at 40 yards; and the standard muzzle constriction that did that, with the period loads, was .040".

W.W. Greener, The Gun and Its Development: With Notes on Shooting, 1881
The Gun and Its Development

and some of those old guns produced extraordinary patterns
The Gun and Its Development

The Field March 7, 1891 Vol 77:325
Sporting Guns and Gunpowders

 

the more chokes you have the better your gun shoots.

the science is settled.