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Discussion Starter · #1 ·
when comparing different gauges in rock breaking ability- the question came up--
if all guns had same choke -say, full and all shot 1 oz 8's-- would the pattern diameter be the same?
 

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That's a interesting question??? Why don't you load a few in each ga. up and let us all know??? break em all. Jeff

Otherwise its just a best guess kind of thing.
 

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If you're going to test it, you must be sure the choke is the same to begin with. That doesn't mean reading "full" on the tube, or even miking the choke & bore. The only way to be sure of comparing full to full is to first determine that the 2 guns actually pattern full.

Full choke is defined as 70% of the payload in a 30" circle at 40 yards, regardless of gauge. So, if your 1 ounce of 8's holds 410 pellets (gotta count' em to know) and 287+ of 'em make it into the 30" circle at 40 yards, the choke is "full."

The choke constriction required to pattern 70% will vary by gauge (say, 35-40 thou in a 12ga versus 24-30 thou in a 20ga), but it must do that to be termed full.
 

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Way back when I started reloading shotgun shells, I learned that for me the two biggest variables in pattern diameter and density were: quality of the shot and the choke. So, to compare pattern diameters between gauges, you'd have to be using comparable shells as well as chokes.

Sort of related - I was goose hunting a couple of years ago on a friend's field. When we were picking up decoys at the end of the day, a neighbor came by and asked what gauge shotguns we were using (12 ga) and told us it was "safer" to shoot a 20 gauge on smaller fields because the shot "would not carry so far" onto neighboring properties.
 

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The pattern diameters for equally well performing chokes are very close to the same for all gauges except 410. By equally well performing I mean each places the same percentage of the overall shot in a 30" circle.

To answer acss' question, the results for 1oz #8 loads in all the gauges would be in gauge order. 12 would have the smallest pattern, then 20, then 28. The reason is the longer shot column in the smaller gauges causes more shot deformation upon firing; creating many more fliers. If the loads were 1oz in 12, 7/8 in 20 and 3/4 in 28, pattern diameters would be about the same.
 

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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 with polyethylene wads are likely better.
Gauge (except .410) makes very little difference in pattern spread, and little difference in density if comparing the same amount of shot. Obviously, more shot = greater density within the pattern. Note the distance for an (about) 30" pattern.

…………………………………………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

I believe within reason (note the current International Trap 24 gm load) the "square load" efficiency theory; shot column height = shot column diameter (12g 1 1/8 oz., 16g 1 oz., 20g 7/8 oz., 28 g 3/4 oz.), has mostly been discarded.

EDIT: I was typing while zzt was posting and believe we're saying the same thing.
 

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Get a copy of the book" Shotgunning the art and the science" by Bob Brister, it will tell you everything you wish to know, if it doesn't then get a copy of "Mysteries of Shotgun Patterns ", Oberfell and Thompson.
 

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acss, Your answer is "YES"!!!!! They will all have the same size pattern no matter what Pattern size you choose???, 10--20--or 30 inches!!! But all 3 different gauge guns (all firing a full choke and one oz of shot) will have the same size patterns at varying distances from the shooting line. break em all. Jeff

What testing should determine!!! Would be these different yardages for each gun (gauge)!!!!! and the pellet density's between the 3 different gauges all with the same size patterns??? break em all. Jeff
 

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Discussion Starter · #10 ·
I can shoot on paper and talk myself into about anything unless its very obvious
was hoping that neal with all his patterning knowledge could inject some wisdom

I just look at all the older shooters and ask "why are they not shooting lighter gauged guns"?
less recoil & easier to move to the target
 

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Presumably, a "lighter gauge" gun will move easier to the target because it's lighter weight? If so, it will likely recoil more, not less, than the heavier gauge gun shooting an equivalent load. There are good reasons why people shoot a 9-10 lb 12 gauge with 1 ounce of shot rather than a 20 gauge.
 

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A 70% pattern will be the essentially same diameter from each of the three gauges regardless of the choke markings. The confusion comes from the fact that not all barrels marked full will throw exactly a 70% pattern at 40 yards.
 

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ou3200: To determine a "70% pattern" you have to draw a 30" circle around the highest shot concentration. So, by definition 70% patterns are 30" in diameter. I don't think this will help the OP. If you mean to say that a circle drawn around 70% of the pellet hits, based on the number of pellets in the load, will have the same diameter gauge to gauge I find that hard to believe. Would you be kind enough to point to your information source? -Ed
 

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ou.3200 ---pellet density and pattern size are two different things!!! and are not necessarily related, but can be. acss is talking about shooting 3 different gauge guns with the same shot payload. None of the gauges he has listed has a recommended payload of one oz of shot. This payload is the normal payload for the 16 ga. gun. So guns shooting abnormal payloads are going to have varying distances of normal patterns, and varying degrees of pattern densities as well. When you say a 70% pattern!!! That number relates to pattern densities. This is not always relative to pattern size as the 28 ga. does not have the same size pattern as the 12 ga., but when comparing the two, each gun may be throwing a 70% pattern with the chokes in the gun. Overbored barrels w/reduced forcing cones tend to throw better pattern density's, when compared to the old style .727 barrels, even with their tighter chokes and the same size patterns. I think I'm starting to confuse myself. lol. lets move on. break em all. Jeff
 

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The 20 Most-Asked Shotgun Questions Answered by an Expert

Choke Pattern Diameter
Approximate Pattern Diameter (Inches)
Choke
..........................10 Yards 20 Yards 25 Yards 30 Yards 40 Yards
Spreader
..............................23............37............44............51............66
Cylinder
..............................20............32............38............44............57
Improved Cylinder
..............................15.............26............32............38............51
Modified
..............................12.............20............26............32............46
Full
...............................9.............16..............21............26............40

Does The 12 Gauge Shoot A Bigger Pattern?

How much larger in diameter is the pattern thrown by a 12-gauge gun than a 20-gauge gun with the same choke?

Everything including the degree of choke constriction being the same, gauge has nothing to do with pattern size. At any given distance patterns from the 10, 12, 16, 20, 28, and .410 will measure approximately the same diameter so long as they are choked the same. The only exception is when extremely soft shot is used. Smaller bores sometimes throw slightly larger patterns with extremely soft shot due to a higher level of pellet deformation during firing, but the difference is seldom great enough to make a difference in the field.
 

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The standard for a true full choke barrel is 70% of the shot payload in a 30" circle at 40 yards (25 yards for .410). Some of the pellets will be outside the circle and the outer edges of the pattern disregarding a few fliers will be the overall pattern diameter. There are many references that indicate that bore diameter has nothing to do with the overall pattern size. Here is but one that I happen to have on my desk. It comes from "Shotgunning, The Art and the Science" by Bob Brister, chapter entitled "The Case for the Small Gauge", page 61:

"About the only thing every gun book in my reference library agrees upon is that gauge has little or nothing to do with the size of pattern, this being, as English writer Gough Thomas puts it, "a function of choke rather than bore."

So, if you are talking about full choke barrels, each throwing a 70% full choke pattern, the overall pattern diameters will be essentially the same overall size. If you are talking about three random guns each with a barrel marked full but untested, the question cannot be answered without additional information. Some barrels marked full may throw modified patterns while others may throw extra full patterns. If you are asking about the efficiency between the gauges it may be more difficult to get full choke performance with heavy shot loads in the smaller gauges.
 

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And to further confuse the issue pattern diameter on paper is the result of shooting at paper NOT a moving target where shot string length comes into play...Brister's book goes into detail on this matter;shooting at a crossing target such as station 4 on a skeet field does NOT mean you will have a perfectly round 30 some inch cloud of shot arriving at the target all at once..
 

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I am curious, what are the definitions of choke performance using the 70% standard for full? How much is modified, IC, IM, etc? I've never really given this any thought.

Comp1, how much does the target move in the time it takes for the shot string to pass the target at skeet distances? I have a real hard time visualizing a target flying into the tail of a swarm of shot when the differences in speed are so great.
 

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You guys have hit upon a pet peeve of mine. The 70% in the 30 inch circle at 40 yards was developed when everybody made the shot shell the same way: Powder, over powder card, felt filler wads, shot. You got the 70% from a barrel that had .040 constriction.

With the use now of plastic wads with shot cups; choke should now just be reference by the constriction. What percentage you get with the shell that you use, you need to find out. Actually you should just forget about percentages and focus on density at various distances that you will be shooting at.

Avaldes, Full .040 70%, IM .030 65%, Mod .020 60%, IC .010 55%, Skeet .005 50%, Cyl 40%.

Jason
 

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Re: shotstringing

Video
Measuring a Shot String With High-Speed Video

Verbiage from Randy Wakeman
A complete database of shotgun patterns will likely never be generated. It has been estimated that it would take 18 billion patterning tests, equating to 8 million man hours of work: and this estimate did not include a shot-stringing study. The December, 1927, American Rifleman gave summaries from L. C. Weldin (ballistics engineer, Hercules Powder) that showed pattern percentages from 19-95 percent with the same load and choke based on 4,000 patterns.

In the October, 1946 American Rifleman a difference of 20% between minimum and maximum pattern percentages was tabulated. Oberfell & Thompson (1957) pulled that in to about 10% variation, assuming same brand of shell and same gun. That remains as close a generalization as can be stated to the present day.

Despite the automatic vagaries of any statement about shot string, Major Gerald Burrard explained it well, and discounted it after his tests. Though a several foot long shot string exists, as the shot cloud is moving ten times (or faster) than any game the shot cloud can only string a matter of inches: a 5 inch shift of pattern center at 40 yards was documented with a 40 mph moving target at right angles. Oberfell and Thompson (The Mysteries of Shotgun Patterns) found the same, finding that it was no more important than the accuracy of the hold of the shotgun itself, and with the 10% variation from shell to shell became even less worthy of concern. This is for direct crossing shots. It is naturally of no concern for outgoing or incoming targets.

Bob Brister (Shotgunning, Art & Science) gave some treatment to the matter, being able to shoot at his wife driving the family car towing a long paper target. However, his tests were outdoors, ignoring actual shotshell patterning deviations. Finally, and most recently, E. D. Lowry revisited the subject in detail, and set the matter to rest for good, concluding that Major Burrard was right all along.

Ed Lowry, ballistician and the director of research at Olin-Winchester, spark shadowgraphs. See "The Effect of a Shotstring" American Rifleman, November 1979



ShotString remains more fable than of tangible value, joining back-boring and gauge selection within reasonable limits as being at all meaningful. Yes, a shotstring has at least the potential to move your shot cloud's center by up to 4 or 5 inches or so at 40 yards. To get excited about that, limited only to faster crossing shots, would require us to somehow ignore that gravity often nets us over 3 inches of drop at 40 yards, and the pattern from your next shell can easily show a 5% loss of efficiency.

And marketing BS courtesy of Western's Super-X "Short Shot String" loads ;)
LIFE
 
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