Straight Dope on Shotgun Chokes
Few things are mused about as often as shotgun chokes and few things are less of a settled matter than, “what choke should I use?” Unfortunately, this isn't likely to change.
It is difficult for us to accept what really means something and what does not. Choke is performance-based, often having very little to do with what a barrel or a screw-choke tube is marked. Choke is also not design-based or “constriction-based.” Though shotgunners have picked up on the word “constriction,” there is no such thing as a choke marked as to actual constriction. The reason is the wide variations in bore diameter. Unless you know the exact bore diameter of a specific shotgun you cannot possibly know what the constriction of the choke might be. Even knowing the difference between actual bore diameter in a gun and the exit diameter of your choke does not necessarily indicate pattern percentage or pattern quality. It means about as much as “room temperature” for no matter how hot or how cold a room gets it is still room temperature.
Tradition has choke as the average pattern percentage of pellets in a 30 inch circle at 40 yards. There are of course by nature problems with this, but it is a tradition, or at least one of them. We should start by asking a few questions. Why do I care about a 40 yard pattern if I'm typically shooting at 20 yards? Why should I care a great deal about a 40 yard pattern if I'm shooting at 50 yards? Why should I care I care about a 30 inch circle when most hunting loads do not have and cannot have a 30 inch effective spread? Why should I care about any of this if my gun does not shoot were I look? Why, indeed. Birds don't seem to care much about beautiful patterns that go where they are not.
We tend to look for shortcuts and like to avoid doing our homework as much as possible. Sorry, folks, but there is no way to avoid patterning your gun at the ranges you want to use it at. It is ridiculous to ask someone “what choke should I use?” when what the choke is marked does not equate to a number of pellets in the kill zone, much less a number of pellets at a specific range. If we want to assume that our shotguns shoot to point of aim and that choke markings mean something specific, then most chokes work in a similar fashion. Blow a bunch of pellets out of the muzzle and of course they have to go somewhere. Ignorance can be blissful, of course, and many wing-shooters choose that path.
It shouldn't surprise us that the notion of choke varies tremendously by type of shell. Just like most all firearms, when you change one variable you tend to change all of them. A specific shotgun and choke combination is going to change in concert with what we feed it. Change the muzzle velocity, you changed your pattern. Change a wad, you changed your pattern. Change shot size, you changed your pattern. Change payload, you changed your pattern. Change shot hardness, shot sphericity, or shot material and you have also changed your pattern. A change in barrel harmonics changes your shotgun, your .22 rimfire, or your centerfire rifle. One specific shell in a specific shotgun will produce unique patterns. No two patterns are truly identical out of the same gun, much less out of different guns with different shells.
None of this will stop the fellow at the gun club from telling you to “use modified” even though he has no clue what your specific shotgun does, what specific ranges you are shooting at, or what variety of shells you are going to be using. He likely doesn't even know the gauge of the shotgun you are referring to and has no concept what constriction a modified choke might be in your gun. To top it all off, pattern percentage does not mean pattern quality. Like a lot of figures, it doesn't always figure. Pellets drop birds and smash targets, not percentages of pellets or markings on choke tubes. “Figures don't lie, but liars figure.” as Mark Twain wrote.
Likely the most important component in pattern performance is “effective spread.” Rather than looking for the tightest (meaning smallest) patterns, a common-sense notion is the largest effective spread at the ranges we want to shoot. One of the worst offenders in shotgunland is the turkey hunter. Not all turkey hunters, certainly no one that reads my reports, but Fred down south somewhere is the fellow.
Fred wants 3000 pellets on a turkey target at 55 yards. Problem is, not all turkeys stop at the 55 yard line. Not all turkeys are geniuses either, particularly when they have their mind on mating. Humans show the same traits at times as well. Despite Fred's 55 yard load, year after year turkeys manage to get called into decoys inside 15 yards and poor Fred misses them every year. Fred never had bothered to pattern his gun at 15 yards, though, or he would know that his silver dollar pattern is a great example of horrifically poor effective spread. God answers our prayers, but sometimes the answer is, “No.” There is no such thing as the best pattern at 15 or 20 yards that is also the best pattern at 40-45 yards. The largest effective spread at 45 yards is unbearably small and dense at 15 or 20 yard, a minimal effect spread. Sometimes, we have to make choices that reflect our personal use. Maybe you know Fred? Fred is one of those guys that answers everything with, “I've been shooting for 50 years.” Certainly, we can all hope that Fred has done a little bit more with his life than pull the trigger on a shotgun. We hope that Fred actually can hold a job, has a family, some friends and might even own a home. I feel sorry for Fred, though. Had he taken the time to pattern his shotguns at the ranges he shoots with the shells he actually uses, he would have enjoyed himself a lot more.
All is not lost, though, and it doesn't take that much effort to get things dialed in for a reasonable compromise. There are no rules, but there are generalizations and trends.
Round shot works better than shot that is not. Harder shot tends to work better as well. Moderate velocities generally offer more consistent patterns than the fastest thing that comes out of the muzzle. A good pattern is the the one that puts three pellets in the kill zone virtually all the time. It just takes a little trial and error to prove to yourself what the most reasonable compromise is.
Factory chokes can generally be greatly improved upon. Extended chokes generally do better than flush chokes; in fact I've never seen them do worse. Only the individual knows what ranges he is shooting at and knows what his gun does with a specific combination. Only those that pattern can possibly determine the better, more consistent, more versatile loads out of their individual shotgun. Ideally, it takes four or five patterns at a specific range to get a representative sampling for the same reason “one shot groups” are meaningless out of rifles and pistols.
The good news is that if you take the time to discover what your individual shotgun does in the ways you plan on using it, it is a one time process that will increase your field effectiveness for as long as you continue to enjoy that shotgun, and for anyone else that uses the same combinations in the future as well. It isn't effortless, but it isn't arduous and the rewards are there for those who take the time to find them.
Copyright 2010 by Randy Wakeman. All rights reserved.