Optimizing Patterns


Thanks Bruce!

I have followed and believed in your patterning stuff. I am a 27 yd registered trap shooter and I am trying to maximize my capabilities with the optimum choking of my gun! At the same time, I am an “AA” 16 yard shooter and have to work my butt of trying to maintain! I feel that I may be giving away a little something shooting the same .035 ” constriction for both events.

If I understand your research, it seems that I should be trying to attain approx an 80% pattern at my break point (approx 30-32 yds) instead of my 95 % present pattern for that distance?! Am I making any sense and do you have any suggestions!

Thanks,

Tom

Dear Tom,

When optimizing pattern percentages for a target at a give distance, it’s important to take into consideration pellet count. Optimal percentages differ as pellet count differs.

Let’s say that you are satisfied with a fringe that has an 80% chance of a two pellet strike. That mathematically equals a 95% chance of a one pellet strike or a 50% chance of a three pellet strike. Not a bad working number for the outermost acceptable fringe of a pattern. Warren Johnson uses this in his “Choke Chooser” and it works well. Obviously, the rest of the pattern inside this fringe will be denser, but patterns are best defined by their fringe.

The math is beyond me, but blindly plugging numbers into ballistician Ed Lowry’s excellent “Shotshell Ballistics for Windows” program isn’t. I’ve learned to leave the heavy lifting to my betters.

Let’s start with 16 yard patterns. You probably use #8 shot because it has plenty of energy for 16 yard shooting. If you use 1-1/8 oz loads, you have about 460 pellets to deal with. I’ll use 7 square inches for the target. A pure edge on 110 is about 6, but a trap target is slightly turned up if you shoot it on the way up, not as it levels. Your optimum pattern size will start right around 77% (22″) and go up to 22.5″ at 85% and then back down to 22″ at 90%. Realistically, any pattern producing 77% to 90% with 1-1/8 oz of #8s at the distance at which you are killing the bird is about right.

Most people take their 16 yard targets at around 32 yards. So, you want whatever choke will print around 85% at 32 yards using 1-1/8 #8s. A 95% pattern at that distance will give you a pattern of about 21.5″. 99% goes down to about 19.8″

Using 1-1/8 oz of #7-1/2s for your handicap, you have only 388 pellets. To maximize those, using the stated pattern fringe, you’d need 80% for a 20″ pattern at the distance at which you take your handicap bird. 85% gets you 20.5″, 90% gets you 20.5″ and 95% goes back down to 20″. 99% gets you about 19″. Note how the lower pellet count of the 7-1/2s gives you a smaller effective pattern. The same thing happens when you go from 1-1/8 oz to 1 oz. Less is less.

Try to pick a pattern percentage right in the middle of the sweet spot because shell to shell pattern variation can be 10%.

Best regards,

Bruce Buck
The Technoid writing for Shotgun Report, LLC
(Often in error. Never in doubt.)

 

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