Patterning Myths Continue

Pattern-testing reveals that with larger pellet sizes, more-open chokes than Full often are required to produce the tightest patterns. Photograph by Rick Adair/

During the past 45 years I have addressed more than 150,000 shotgunners worldwide in my nontoxic-shotshell seminars. I also have worked with a little more than 10,000 of them in patterning and shooting clinics. I have run another 4,000-plus shotgunners through a series of five peer-reviewed scientific steel-versus-lead bird shooting tests. After all this I am shocked that certain patterning myths that were prevalent when I began in about 1975 still are present today. 

Tighter Chokes Always Yield Tighter Patterns

This one just won’t go away. I firmly believe this is due principally to the fact that most shotgunners never pattern-test their choke-and-load combinations—and of those who do, many do it inadequately and/or incorrectly. If they did it correctly and adequately, they quickly would learn that ever-tighter chokes do not necessarily yield ever-tighter patterns. 

Here’s how it works. It is true that a big jump in choke constriction, such as going from Improved Cylinder to a basic Full, will print tighter patterns with all shot types and almost all bird shot (sub-buck shot) sizes at any given distance. But it is not true that once you reach Full choke for a given gauge, continuing to increase the constriction (the difference between the internal diameter of the choke and the internal diameter of the bore) so it becomes tighter will necessarily tighten the pattern. 

Even a modicum of pattern-testing quickly reveals that after reaching Full choke, tighter and tighter chokes become counter-productive. In short, for any given pellet size, a choke constriction can become too tight. Instead of producing denser and denser patterns, ever-tighter chokes often cause pattern density to go the other way. This is especially true as shot sizes become larger, and especially after shot sizes reach No. 2 (.150") or larger. Pattern-testing quickly reveals that with larger pellet sizes, more-open choke constrictions than Full often are required to produce the tightest patterns. My pattern-testing repeatedly has revealed that with hard shot types in particular—like steel—pellet sizes No. BB (.180") and larger almost always pattern tighter through more-open choke constrictions of Modified or Improved Modified, especially at longer shooting distances. So don’t get sucked into the idea that very tight chokes automatically are going to give you super-good long-range patterns. Almost always they will not. 

A Choke Patterns Everything the Same

Another way to put this is: However Choke X may pattern with Shot Type Y and Shot Size Z, you can count on it to deliver the same patterns with the same shot size of every other shot type out there. This myth is most commonly adhered to by shotgunners who simply have not or will not take the time to pattern-test all the shot types and shot sizes they’re considering shooting through a given choke in their shotgun. So as an example, our shotgunner goes to the correct patterning distance of 40 yards and pattern-tests a three-shot sample of a given load of steel No. 4s (.130") through his Full choke. Very good. But after that when he switches to lead No. 4s, bismuth No. 4s or HEVI-Shot No. 4s through the same choke, he never takes the time to pattern-test them because he assumes that all No. 4s, regardless of shot type, now will pattern the same as his specific load of steel 4s. Big mistake.

While this saves the time and trouble of pattern-testing the other loads, the shooter then proceeds through a shotgunning world of blissful ignorance. What he quickly would have found by doing the patterning work is that none of the other shot types in pellet size No. 4 pattern the same through his Full choke as did the original load of steel 4s. Lead and bismuth 4s generally will pattern quite a bit more open through a Full choke than steel 4s, and HEVI-Shot 4s may pattern tighter. But how much of a change occurs with any of the other shot types (or other shot sizes) can be determined only through actual pattern-testing. 

One Uncounted Pattern Shot Tells All

The last great patterning myth that, depressingly, I find growing is the idea (as evidenced by Internet performers, especially those hyping a given shotshell product on YouTube) that the following is all you have to do to determine if your load is going to be lethal: Set up any size patterning target at 25 to 35 yards (saves walking), fire one shot, go up and then eyeball it. Forego any kind of effort to follow the universally accepted scientific procedure of scribing a 30" circle around the densest registration of pellet holes, and especially don’t waste time counting any pellet holes. Now if the uncounted pellet holes simply look “good” (whatever that means), emphatically declare to the camera, “That’s a dead duck!” This is how far things have degenerated. In fact, what is learned and measured by this completely inadequate, one-shot, eyeballed approach is precisely nothing about load effectiveness or lethality. 

I would hope that we all could do better. Responsible shotgunners will, and conservation considerations demand it. 

To consult with Tom Roster or to order his manuals on reloading lead and bismuth shot, reloading HEVI-Shot and HW 13, or having shotgun-barrel-modification work performed or his instructional shooting DVD, contact: Tom Roster, 1190 Lynnewood Blvd., Klamath Falls, OR 97601; 541-884-2974,

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On the cover: Incoming canvasbacks photographed by Tom Martineau/

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  • Thank God for Tom Roster. He’s been saying these things a long time, and some limited work of my own following his instructions has confirmed for me that he is right.
    Considering the type of shooting I do, I never use Full choke anyway. It is a sign of the times that when I was a young teen and my Dad gave me my first shotgun, it was a M12 Winchester pump in 16 ga with a full choke. I knew nothing about patterning but found that I had a lot of misses!
    As an adult with 12 ga guns, I have gone to more open chokes with steel duck loads, and in fact many guns advise against full choke with steel anyway. The learning curve with shotguns/loads is just slow, and always will be, I’m afraid.

  • Tom, good info. Love your writing style. Newbie here. I was looking at a used, 1960’s Remington 870 Wingmaster with a 28″ fixed full choke barrel. Thinking it might be good for ducks and geese at longer distances. You know, those ducks that see the decoys but ignore them and fly straight over. Is there a Bismuth shell that will (might) pattern well for this shotgun … or did I miss the whole point of your article which is that I have to test a bunch of different shells to find out? Thanks. Jim

  • … I’m trying to figure out (before buying) i
    f the used Rem 870 with a full choke and bismuth would pattern tighter than a more modern shotgun shooting steel out of a modified choke.

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