The recent thread on jug choking reminded me of a question lingering in my mind from a recent Julia's auction catalog entry. Does jug choking produce a "hot center" in a pattern and is this desirable?. The entry in question is from the description of King Alphonso's hammer pigeon gun:

"Bore diameter: left -.730, right – .731. Bore restrictions: left – .031 with .001 recess (full), right – .033 with .001 recess (full); (This is standard Purdey boring for pigeon guns. Recess giving superb tight patterns with a hot center). (Factory records indicate “both fullest choke”.) "

I think that you will find that 'hot centers' are the norm when using quality shot and the harder the shot and the better its sphericity the more that holds true, regardless of choke/constriction. It has been an observed phenomena since the 1880's in trials run at that time when few guns were choke bored.

All chokes produce patterns with hot centers. I've seen many hundreds of patterns in my life, and the only gun I ever saw that shot a pattern that didn't have a hot center shot donut patterns every shot, a B2000. That said, some are hotter than others.

By the way, the choke in that B2000 was very slightly honed and it went to throwing normal patterns ................. with a hot center.

SRH

Note that patterns are near normally distributed --- from muzzle to the ground. The concept of hot centers is a misunderstanding of the distribution. The more the choke effect the greater distance for given pattern diameter. That is to say at distance X aIC pattern is the same as a full at distance Y.

DDA

When I, and others, say hot core we mean that the density of the shot distribution increases from the edge of the pattern toward the center. You can break a clay bird, showing you the belly, every time with a .005" choke at 30 yards if you have the bird in the center of the pattern, because of increased density. If it is on the edge of that pattern the probability of a break is the lowest, because of lack of density. As the bird is nearer the center of the pattern the probability of a break increases, to a maximum percentage at dead center. This is because of density .............more at the center, lessening as you move out towards the edge. Thus, the colloquialism "hot center".
I do not agree this is a misunderstanding ..............it is an observation of hundreds of patterns and tens of thousands of breaks. Center of pattern = smoke, fringe of pattern = chip.

I would like to think we mean the same thing, Don, but I'm saying it in layman's words and you in scientific terminology. "Normal distribution" for a typical shotgun pattern is for it to possess a distribution that has higher density as you move from the edge towards the center.

SRH

That is very helpful. If anyone has comments on the combination of full choke and .001 recess choke specified by the King I would love to hear them, especially as to how the combo is more successful at producing a hot center.

Stan, I do think you and I have a common understanding of patterns and how they work. I use "normal" in the statistical meaning of the specific "bell curve" distribution. My issue with "hot core" is that shooters seem to me to try to divide patterns into "hot core" and "fringe" and lose the idea of a relatively smooth change in pellets per square inch from center to edge. Say 5 pellets per square inch in the center, 2 pellets/sq inch half way out to the edge, and less than 1 pellet at the edge.
DDA

For an interesting discussion of chokes, especially Purdey chokes, check the gunsmithing by Bill Nittler video. I had it in the past but have since lost it. Quite interesting.

I seriously doubt that it has any effect per se. Choke effect is a relatively smooth transition by thousandth of an inch from cyl (0.000 constriction) to full (about 0.040). We generally use about 0.005" as constriction increments as steps.

DDA

We're on the same page, Don. Just different terminology.

SRH

This is a fascinating but seemingly unsolvable problem to discuss.

I have no engineering or higher physics education, but I’ve read entirely too many old gun books and shot so many patterns on a plate, that I’m a waivering, doubtful, bitter clinger to the idea that maybe, perhaps, there is still enough mystery and art left to shotgun patterns as to occasionally allow a well choked gun to escape the long dead hand of Herr Dr. Gauss.

To restate the original post’s question to suit the hypothetical:

1. Is is possible to cheat normal Gaussian distribution of shotgun patterns by using a recess (jug choke) before a full (.35-40 thousands) choke to obtain “hot centers” where the pellets in the center are denser than normal,,,

2. Or do the iron laws of normal (Gaussian) distribution mean that no matter if we lengthen forcing cones, use conical, elliptical, parallel, recessed, or swaged or collet chokes, folded crimped hulls with plastic, cushioned, protective wads with nickel plated shot,,,,or not,,,mean that all shotgun patterns remain the same, only at different distances from the muzzle?

If the scientists are right, then better patterns are therefore impossible, we can only shoot smaller or larger circles on the plate, at a given distance.

Almost, I am persuaded to be a scientist about choke.

But with quavering faith, I read again my W.W. greener and Bob Brister, shoot a few more patterns on a plate, and the spark of hope still flickers, there might be the one, true choke that produces hot centers, but not too hot, minimal shot balling, patchiness, and fliers, and spreads quickly an inch per yard out to twenty yards and slows the spreading after thirty yards, almost “holding” that pattern out to about forty yards, and leaving a hot center to break targets and kill birds out to sixty yards, perhaps a bit beyond that.

I even think I own a few of those artistically choked guns.

They tend to be 12 gauge guns with about 12-13 thousands constriction.

Not quite a light modified, but an improved cylinder, plus.


There might be such a unicorn of a full choked shotgun, if there was a recess choke of a thousandth just before the choke, that makes exceptionally hot cores.

If not, it’s pretty to think there is.




,

You can start with Neil Winston

http://www.claytargettesting.com/index.html

and his EXTENSIVE postings on trapshooters.com

all data based fact

Truth, but in good humor. ;-}

DDA

Winston is under the influence of Dr. A.C. Jones, the worst nemisis that faith based chokesmiths encounter. Dr. Jones, is the AntiEyster.

There are times I believe Dr. Jones is correct, and there is no salvation or escape from normal distribution of pellets in the circle.

But then, why do spreader loads work?

Has all the treasure and labor spent on harder, rounder shot protected from deformation in forcing cone and choke, been wasted?

Why do the makers of card shooting (turkey shoot) guns tend to gain and keep their reputations by repeated wins of their guns at contests?

Was Bob Eyster, just a shyster?

And why did all the gun scribes from Greener to Brister believe that choking was both art and science?

I almost believe Jones is right.

There are advantages to a purely normal distribution of all patterns.

For one thing, you could shoot all patterns at ten yards, measure the circles, and be done with patterning.

That is where to start patterning. A full choke pattern is close to five inches, maybe six, at ten yards. A cylinder bore pattern at ten yards is about fifteen inches, maybe a bit more. All the other chokes will print circles between five and fifteen inches.

Then, it’s fun to start stepping back to twenty, thirty, forty, yards and further, to see how even they are, how quickly they spread, if they have hot cores, or excessive shot balling, or fliers.

If Dr. Jones is right, patterning shotguns beyond ten yards is just purely chasing moonbeams.

There’s no fun, in that.

We’d rather pretend we are searching for grails.

Your theory of a choke just ahead of a choke has already been marketed. It's not a jug choke ahead of choke, but it is "two in one". It's called the Brain Choke (ironic, eh?). You can read all about it here.

https://brainchokes.com/en/inner-profile/

Note the street address (color added)


42A Tzavella str, N. Psychiko
P.O. 15451, Athens Greece

I wanted to say, you can't make this stuff up, but somebody did. That said, if someone would donate me a choke tube to fit one of my shotties I will be happy to do an impartial test on my plate. After all, they were only looking for the same thing we all would like to have ...............equal density from edge to center to edge. Holy grail, indeed!

SRH

Do you mean the late Ken Eyster, with his art and science carried on by son Jim? Kenny sure attracted many of the top sporting clays shooters 'though many never talked about bore and choke work by the man.

Jug chokes? That's what choke tubes are, and I suspect we all have one or two lurking about in the safe. Mine print cores, just like fixed chokes. I doubt you can look at a pattern and say it was generated by a fixed choke, a jug, or a choke tube, so I'm going to stick my neck out and say there is no verifiable advantage (desirability) to a jug choke.

Yes, I meant Ken Eyster. Thanks for correcting me. He’s not the only custom chokesmith.


If Dr. Jones is right, then all the custom chokesmiths that have ever lived, or will live, are in the same category as the certified psychics and telepreachers you see on cable television.

According to Dr. Jones, there are no fliers, no hot cores, and no patchiness, and even shotballing, are all merely a normal distribution curve. All choke does is press down the shot charge, so that the pattern spreads according to normal distribution later rather than sooner.More choke effect, smaller circles, less choke effect, larger circles. The dead hand of Gauss determines all patterns,,,,except spreader loads.

The disciples of Dr. Jones, say that all patterns will be the same, just at different distances from the muzzle, and they spread their heresy to all nations. Hard shot, just is affected more by choke. Soft shot requires more choke. All choke can do is make smaller circles.

All the old time chokesmiths, preach and practice the religion that better patterns are possible by harder, rounder shot, and better choke work.

If Dr. Jones is right, all the chokesmiths are wrong.

You can have science based on experimentation or "faith-based".
The two camps will never be reconciled.
I'm with Dr. Jones and Neil Winston.

Welllll, lemme see now - what does the data support?

Let's look at the data available obtained and analyzed either supporting the barrel/choke gurus or that that they themselves offer up. Oooops - there ISN'T any!!! Nothing but opinions!
Now let's look at the data on the other hand. The problem is where to start with the wealth of data supporting the anti-gurus. As I suggested before, Mr. Winston is an excellent entre to that fund of information.

It's not a matter of faith or belief. What does the data support? That is the only real world approach.

And in the final analysis it is still only a shotgun. Get over it.

I’m a doubting Thomas, but still barely with Greener and Brister, and all the others that have grasped for the grail of “better” patterns.

And I do think some reconciliation of science and art of choking shotguns can be made.

Even Dr. Jones looks at the corrupted patterns of spreader loads and makes exception for those.

And while W.W. Greener certainly was a good promoter, he believed in himself, and wasn’t a fraud. Neither was Brister or Eyster. They all recognized all patterns have a bit of the roulette wheel to them. They said patterns were the result of science, art, and chance.

If you have an old gun with a Polychoke, it’s easier, but in these modern times you can take any shotgun above .410 gauge that has interchangeable choke tubes, and conduct this simple test on a patterning plate, or on butcher paper.

Take a box of shotgun shells, all the same load, factory loads leave less to chance, and a shotgun with a device to vary the chokes,,,that’s the same type of choke. Measure exactly 30 feet back from the pattern plate. Make a mark on the ground. Put the end of the muzzle directly over that mark and fire a series of patterns at the plate, from true cylinder bore (threads for a choke tube gun) to the tightest choke you have.

Here’s one I did with an Auto Five Light Twelve with a Deluxe Polychoke.

https://imgur.com/a/DFGJ3

Here’s another using six extended choke tubes with an SKB 685, top two rows, the bottom row other guns.

https://imgur.com/gallery/RZMkd

What will always happen, every time you try this, will be as the choke constriction gets tighter the circles shrink. You don’t need to average patterns or make calculations. At ten yards 40 thousanths of choke makes a smaller circle in the plate than 25 thousandths which makes a smaller circle than 20 thousandths, on down to cylinder bore, which will have the widest circle.

This is the ten yard patterning shortcut Jack O’Connor wrote about in “The Shotgun Book”, but he didn’t claim to discover it.

Now, if the scientists are right, it should be possible to shoot a wide cylinder bore pattern at ten yards, of whatever size circle the choke and load shoots, say 15 inches, and then put in a full tube (or screw the Polychoke down to full) and start stepping back to where there’s a 15 inch full choke circle pattern on the plate, and there won’t be any differences (except normal distribution) between the 10 yard cylinder patterns and (let’s say) 15 yard full choke patterns.

I’ve tried to do that, but when I try it, the full choke pattern can be made to shoot an identical size circle, at some further range, but it will have a denser core and not be as evenly distributed as the identically sized pattern from the cylinder bore shot at closer range.

And if you shoot the cylinder at 15 yards, and step back far enough with a full choke to duplicate the same circle, the differences are even more apparent.

The scientists may either deny that’s so or say that’s merely normal distribution, and I’ve not actually duplicated the circles.

But try it and see, and I think you’ll cling to the faith that it’s possible to have better patterns, not just tighter ones.

Brister named his book well.

Patterns are the result of art, and science, both.

I am not sure that the discussion of pattern variability is JUST about choke. Bill Nittler regulated the barrels of a couple of guns for me and he said that the interior profile of the entire barrel had an influence on the patterns obtained. He actually was able to produce the exact pattern percentages (within 1 % - 2%) that I requested with the ammunition that I provided.

My question is... how much actual variability is there between patterns produced from the same gun under repeated, identical test conditions??

There is sufficient evidence (with photographic proof) of powder varieties yielding differing core densities with otherwise identical reloads of the same shot charges through the same barrels that I'm comfortable altering results via shell choice. To be fair, I've only had one barrel jug choked in order to restore choke rather than an attempt to improve its existing performance.

C'man,

It's according to what you mean by variability. No two patterns are the same. So, there is variability between every pattern ever shot. Are the voids in the pattern in the same place every time the same gun and load is shot? No. I have only seen one gun in my life that did that, and I have mentioned it numerous times. It shot a donut pattern with a hole in the center .............everytime. That is an anomaly.

But, there is enough certainty that a cylinder will shoot a cylinder sized pattern, and that a modified will shoot a modified sized pattern, that we can pretty well bank on it. IOW, the overall diameter of the pattern will be very reliable, while the location fo the patchiness will not.

That may or may not be adressing your question (?).

SRH

P.S. This is assuming the exact same load is used.

Stan - - That answers most of my question. I was interested to know if anyone might know the variability of distribution - the percentages that show in the 30" circle.

I expect that, while the actual percentage of pellet strikes inside the circle are fairly consistent, it IS a Monte Carlo distribution and the percentage may vary some amount shot to shot under identical conditions. Maybe 5% or so?

Good question about the percentages. I haven't a clue, but would hazard a guess that they are more than 5% in variability.

SRH

If only we could get that perfect distribution of pellets, evenly in a pattern. Then on crossing birds I want he pattern to be either a horizontal oval or a rectangle to give me even getter chance of hitting my target. Bought a screw in choke tube which was designed to flatten a pattern but all it did was shred wads, give extra muzzle jump and ruin patterns. It is in a drawer somewhere. More gun junk like we all accumulate.

Years ago, before we had screw in choke tubes for tubes in Skeet guns, I had a friend order a set of tubes with .020 chokes in everything. From there he patterned everything as he reamed out the chokes to get his “best” pattern distribution. To him he had the perfect patterns and guarded the information for years. After he passed away I bought his tube set and found his perfect constructions were slightly tighter in the 20, .010 and .012, 28, .008 and .013 and the .410 was .013 and .016. So he was slightly tighter than normal but when you patterned the tubes, different loads gave vastly different results. With his loads they gave very nice patterns.

He picked his “load” and only considered that load when he patterned his gun. Different loads would make more open or tighter patterns so great that I concluded plus or minus one degree of choke could be just due load or shot size chosen. Made life simpler when I found a few loads which would give me what I wanted in patterns without having to alter chokes or change chose tubes. I am for any thing I can do to a gun without altering the gun in a permanent way. I’ve seen too many guns with reamed out chokes already to add more to the group.

Amen. Excellent post.

SRH

Jon, the first gun I ever had a choke opened on was done by an amateur, and the muzzle shows a strong bias toward one side. That barrel shoots sort of a left to right smear rather than a round pattern. I think it helps on a dove going across in a hurry...Geo

If it's going the right way.

SRH

This fellow had been a machinist in his younger days so he did the job properly. He used a set of piloted adjustable reamers taking a couple thousands off, then polishing and then patterning. True to being thorough he did ten patterns of each tube and said if he got one bad one out of the ten he would do a five extra. I can only guess he did hundreds of pattern before he was done. He did this for three sets of tubes. He only shot the "selected" shells for competition and serious practice. The rest of the time he shot reloads like the rest of us but he patterned them extensively as well. Them man was dedicated to say the least.

I've got to find that choke tube I bought. It looks like a figure eight laid sideways with two projections, one in the center top and one center bottom. The projections were designed to retard the wad, while the pattern was supposed to be a flattened oval. What the projections did was shred the wad so plastic confetti would float away and the pattern was crap to say the least.

Please, guys, read Jones. He did serious work on pattern variability. It is big. If it was small, we wouldn't need ten patterns to get statistically reasonable pattern data.

DDA

I've read Dr. Jones but do not agree with all his conclusions. One book is not the answer unless it is the Bible. I do not live and die on the patterning plate but I do think it has a real place when you are working up long range loads for specific applications like pass shooting birds. Then I do the math and determine if my load will have sufficient energy, at long range, to kill the bird. Shot on target is all that matters, if it has enough energy to penetrate and do its job.

Great long range patterns are only useful if you can use them to take your bird cleanly. Different with clay targets, which do not suffer if "wounded". One thing I learned was that I could get very useful hunting patterns by changing shot size, then changing velocity to make a load much better at long range. In short, big shot going slightly slower, works better at range than small shot starting out faster.

I agree - retained energy is just as important as pattern when bird shooting. And, yeah, slower is usally better - within reason. Most of my loads are at 1150 - 1200 fps MV.

What size bird is Brister giving that 1 Ft Lb of energy for. It seems quite obvious to me one would need more Ft Lbs for a Goose than a Quail.

+1 for 2-p. Patterning is a different issue than shot size, velocity and retained energy. You do the shot size and velocity for needed retained energy and then test for pattern. However, plan on shooting 10 patterns per load with statistical analysis if you really want to know.

DDA

Brister stated that this was a MINIMUM retained energy for effectiveness. I guess he figured that the shooter would use common sense.

My "Common Sense" tells me for a big Canada I would want as a bare minimum at least 3 Ft Lbs, preferably more. Basically this table seems worthless to me for any bird weighing in at over a pound, even a bit questionable for birds of 1 lb, unless you fill them so "Full" of shot that one pellet will find a vital spot.

No chart can take into account the angle of the shot. From taking nearly a thousand geese I can say with absolute certainty my least favorite shot is the classic Texas brain shot on geese. It is just so hard to get good penetration, to get a pellet into a vital area, for a kill which occurs quickly. A head on or side to shot is much more dependable in my experience. More geese die from wing injuries it seems, from the Texas brain shot, than from vitals being injured. And my last retriever came to hate retrieving cripple geese, with a broken wing. Seems the geese are a bit grumpy which make for a nasty retrieve. I hate when the dog gives me that shoot better look or fetch them yourself attitude.