Before continuing with this post, please review http://www.montanaoutdoor.com/2012/12/more-on-shot-patterns-with-colonel-smoothbore/.
Here are a few ways we can fill the “holes” in our shotgun patterns. For the sake of brevity and simplicity, we’ll just consider 12 gauge loads, but the same principles hold true for the smaller gauges.
If you have a gun with interchangeable chokes, you can start with a constriction change. If you are using steel or other non-toxic shot, I suggest that you try a more open choke. As an example, go from a modified to a light modified or improved cylinder. This change will help eliminate the “blowing” of the pattern when the non-malleable shot is overly compressed as it passes through the choke. If you are using a lead load with a heavy shot charge (1 ¼ ounce or more) and large shot size (4 or larger) the same process will likely lead to fuller, more even patterns. If you are using a light load (1 1/8 ounce or less) try a choke with more constriction. For example go from a modified to an improved modified or even a full choke. This procedure is especially effective if you are using smaller shot sizes, like 8’s and 9’s.
If your gun has a fixed choke, then you will probably have to change your chosen load. First, try the same payload (e.g. 1 1/8 ounce) but with a different muzzle velocity. For example go from a load with a MV of 1120 f/s to one of 1200 f/s MV or vice versa. If that doesn’t work go with a lighter payload, say 1 ounce instead of 1 1/8. Often times a small change in shot size can make a big difference in achieving good patterns (e.g. size 4 to size 6). Often a smaller shot size will result in better patterns. As I have stated in past posts, I use size 6 shot in either 1 or 1 1/8 ounce loads for all my upland hunting. That’s about 50 years of great patterns and 50 years of mighty tasty table fare; it really works.
In future posts we’ll look more closely at choke choices, but once you find a shotshell load and choke combination that works in your gun, stick with it. If want to try something new, be sure to pattern the combinations before you head into the field or onto the range. If you have any problems or questions about patterning or other firearm related subjects, send them to me at firstname.lastname@example.org.
Be safe and good shooting.