Gauss, Yet Again

G’day Bruce.

How’s things? Just finished catching up on the latest in the tracts and was interested in reading several articles on choking.

I used to shoot a fixed choke gun until I had it fitted with the very satisfactory Briley thin wall chokes, the reasoning being that a gun that miked out with extra full in the top barrel and three quarter in the bottom was more than a bit tight for sporting. Choking that tight simply had to be costing me a target here or there. One target in a hundred, even two or three hundred, is all it takes when competing in AA.

The elusive happy medium is what we all search for and in my own experience, I would rather be shooting more open chokes than closed. The rationale being that the score card doesn’t record what the target looked like when I hit it, or how much it smoked, only that I got a visible chip.

My view these days is that if I see smoke, I’m overchoked – too tight. I enjoy seeing my targets hit hard, but not smoked. I’ll gladly give up the momentary satisfaction of a target vaporising before my eyes, for the win at the end of the day. I’m not a gaussian devotee but experience and observation, my own at least, tell me that chips win more often than smoke balls. In sporting anyway. Quarter and half is ample for me and I do all right. I readily admit to twiddling once I see a bird out at 40+ yards, if it’s edge on, but only to three quarter. 32 grams of 7 and a halves do the rest. For everything, regardless of choke.

I’ve yet to miss a target and think that pattern had anything to do with it. I knew I was behind, in front, over or under, to the right or the left – but never on and not have a break. Funny how they’re usually the average distance type targets too. If the head’s in gear and I put the shot where the target’s going to be, it’ll break.

Just thought I’d offer up a view and see what experiences, opinions and thoughts on the matter, the Technoid might bestow.

Yours in shooting,
Having fun,


Dear Peter,

Open chokes, good. Tight chokes, bad. Twenty years ago you would have been preaching to the choir. Now I am not so sure. Today, if I have to choose between overchoking and underchoking, I will take the heavy choke every time. I have been over this before in Shotgun Report, but it bears repeating from time to time.

Obviously, everyone would agree that having the correct choke in the barrel is an asset. It is what constitutes the correct choke that is at question here.

A lot of people feel that if you smoke a bird when you perfectly center it, you are too tight. They loosen up a choke like that under the rationale that they are wasting potential pattern diameter. Enough is enough. Too much is wasted. Those extra pellets in the center that cause the smoke would be better used if they could be moved out to thicken the fringe and provide a larger killing pattern.

This certainly makes sense in theory, but it is wrong because the theory behind it is just plain not the way patterns work in the real world.

In spite of what you have heard or read to the contrary in old books like Greener’s and such, there is no such thing as a perfectly even pellet distribution from the center to the fringe of a pattern. All shotgun patterns have to obey certain mathematical laws. One of them is the law of “normal distribution”. This is the Gaussian or bell-shaped curve that applies to any collection of cojoined random events- such as a fist full of pellets flying down range..

Translation: ALL SHOTGUN PATTERNS ARE HOTTER IN THE CENTER THAN AT THE EDGE. Super spinner chokes, spreader wads, high antimony shot, duplex loads, special multi-fingered wads, hyper velocity- none of it matters as far as the basic laws of mathematics are concerned. ALL SHOTGUN PATTERNS ARE HOTTER IN THE CENTER THAN AT THE EDGE. You gotta Trust The Technoid on this one. Honest.

Ballisticians call this mathematical fact “central thickening”. In shotshells, they try to minimize it to the extent possible in order to approach the paradigm of the perfectly even pattern, but a 2:1 ratio between the center half and the outer half of a 30″ pattern is considered pretty good.

Now apply this hot core phenomenon to practical pattern observance.

First you have to define the number of pellet strikes which you will use as your minimal acceptable pattern fringe. Warren Johnson in his most excellent “Choke Chooser” uses an 80% chance of a two pellet strike. Although this is much easier to figure out on the computer, you could just draw a series of 1″ circles around your pattern and keep moving outward until you find a circle with a pellet count that fits the definition. You would need a pellet count equal to the area of the particular 1″ ring divided by the area of the target times two pellets. And you have to get this count 80% of the time you shoot the pattern. Remember that the target area changes from 6″ to 15″ depending on how much it is turned so you want to take that into account too.

At any rate, one way or another, you have to define the minimally acceptable pellet density that you will accept at the outer edge of your pattern. Now, remember the rule that ALL SHOTGUN PATTERNS ARE HOTTER IN THE CENTER THAN AT THE EDGE? If the edge of your pattern is the minimally acceptable density by definition, what does the center of your pattern have to be? IT HAS GOTTA BE TOO DENSE! Has to be. Got to be.

If the center already is so thin that it has the minimal acceptable density, then there is NO fringe because the pattern mathematically has to get weaker and weaker the further it is from the center. If you start with minimal acceptable, you have no where to go but to unacceptable. Your center and your minimally acceptable fringe become one. Your acceptable pattern is mathematically the size of a pencil point.

This is why, if you center your bird, you want to see a heavy hit. Only by having a center that is too hot can you be sure that you have an acceptable fringe some distance from the center.

Obviously, you can go too far and have a pattern denser (and thus smaller) than it needs to be. You can go to far in anything. The point that I am trying to make is that in order to have the largest effective pattern possible for the particular distance and target presentation, you are going to want to have a heavy hit when you hit the bird dead center. Maybe you don’t want to see an atomic cloud of smoke, but you do want a heavy break. If you just get a nice krinkly hit when you center the bird, you can tell that you have not maximized your pattern diameter.

Unfortunately, just how heavy a hit and how far from the center you can move your minimal acceptable fringe pattern is a matter of testing. None of us can test every possible distance combination so we often have to eyeball the breaks and guesstimate.

The point to all this is that when you do select your chokes, bias to a heavier break when you center the bird, not a lighter break. If you are not sure which of two chokes to pick, pick the TIGHTER one.

It took me a lot of years and a whole bunch of shots to realize this because it is so counter-intuitive. We all want the biggest pattern possible and it is quite natural to think that if we smoke the bird we are “wasting” pattern. It turns out that just isn’t the case. Cigarette smoking may be bad, but target smoking isn’t.

Boots off. Beer open.

Best regards,

Bruce Buck
Shotgun Report’s Technoid
(Often in error, never in doubt.)

This entry was posted in Shotgun related, Shotguns. Bookmark the permalink.

One Response to Gauss, Yet Again

  1. Richard Fleming says:

    Bravo, Bruce! When I see shooters choking IC at 16-yard ATA, I feel sorry for their poor thinking, but they can’t/won’t be convinced. I’ve even seen some shooting 27-yard Trap (non-registered, of course) with 7/8 oz of #7 1/2 shot and with a LMOD choke! One might break a 25-straight about once-per-year with such a setup, but it’ll be IN SPITE of this, certainly not because of it! My 1960-vintage Superposed Lightning Trap is choked F/F. Every 100 as well as every excellent score I ever shot (not many of each) was done with a fixed FULL!

    I have a “Choke Chooser” and find that one can “get-by” with less choke than recommended, but not by much! The math here is sound. (I am a math-geek with a Ph.D. in theoretical physics.)

    OTOH, I’ve seen some shooters choke LMOD or tighter for American SKEET. This is also ludicrous.

    I have an old VHS tape on choke vs. “effective” pattern diameter by Gil Ash and another luminary (I THINK it’s entitled “Chokes and Loads for Sporting Clays”.) which shows that, at certain distances, the tighter choke may have a larger effective pattern. For example, at 40 yards, a FULL produces a larger effective pattern-diameter (on clay targets) than a MOD.

    I once asked Gene Sears if screw-chokes in a Perazzi might afford me any improvement over the really tight factory FULL Chokes and he replied that I might gain one-or-two targets per annum!

    My mediocre experience at age 73 years dictates: “Choke for Smoke in Trap, Shoot Skeet Chokes in American Skeet!”, and “Do not rely on anecdotal evidence which seems to contradict Probability Theory and Calculus!”

    Of course, I could be wrong. My HS math-teacher of 55+ years ago once said, “I’m not infallible, I just don’t make mistakes!”

    Please don’t feel obligated to print this as some will think I’m obstinate while others might conclude that I’m just opposed to progress. (Both these things are probably true.)

    Best regards,
    Richard Fleming

Leave a Comment

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s