Assumptions That Can Bite

Man hunting a bird
Because most gamebird shots and clay-target presentations in the US are level or rising, a low-shooting gun is going to result in some missing. Photo by Steve Oehlenschlager/

The longer I’ve worked with and written for shotgunners (40-plus years now), the more I’ve come to realize that a large number of them make all kinds of performance assumptions about their guns and loads but never do any testing of them.

The problem with this is that shotgunning is a complex subject. There are myriad gauges, chokes, shotshell loads and shotguns that have to be narrowed down to find the best performance fit for each shooter’s intended shotgunning activity. And the bottom line is that this can really be found only by testing empirically. 

Assumption 1: My gun shoots straight

Based on the hundreds of shotguns I’ve tested for point of impact (POI), no one should ever count on a shotgun shooting straight. I’ve recorded a consistent ~15-percent rate of the shotguns I’ve tested exhibiting POI errors. Every shotgun should be tested for point of impact as soon as it’s purchased. Many are the shotguns I’ve tested for POI that shoot high right or left, low right or left, or straight-on high or low. It hasn’t mattered how expensive they’ve been either. If your shotgun when actually tested exhibits any of these POI shortcomings, you’re in for some gun-caused missing that you wouldn’t have been able to explain. The worst is having a low-shooting shotgun, as most clay-target presentations and gamebird shots in the US are level or rising. 

Assumption 2: Chokes conquer all

Perhaps the biggest and most common faulty assumption among shotgunners is that just by purchasing Whiz Bang Choke Tube X, they can shoot any load and shot size through it and it will pattern great. I assure you that based on the tens of thousands of shotshell rounds and hundreds of loads and shot sizes that I and my research assistants have pattern-tested, nothing is more unpredictable and complicated in shotgunning than how a given choke—integral or screw-in—is going to pattern with a given load and shot size. Many are the cases where popular choke tubes I’ve pattern-tested with certain loads have either delivered mediocre patterning performance or outright failed in the patterning department—especially at distances beyond 40 yards. I’ve concluded from all of this research that there is absolutely no way to accurately predict how any integral choke or choke tube is going to pattern with any load and shot size. The only way to know is to take the time to empirically pattern-test and count all of those little holes in the patterning paper or the pellet marks on the patterning plate. 

But I have been horrified to learn two facts by distributing my pre-training and shotgunning-seminar surveys to participating shotgunners (more than 4,000 worldwide):

  1. Of those who say they have done some pattern-testing, about 60 percent detail incorrect distances (usually too short) and/or insufficient sample sizes (usually just one shot) and/or target surfaces too small to record all the pellet strikes.
  2. Even worse, the majority indicate they’ve never pattern-tested at all! The reason? They just don’t want to take the time and effort to walk back and forth to count the pellet strikes. I’m serious; it’s that bad. I’ve had participants in my shotgunning clinics who during the patterning exercises wouldn’t walk downrange to count their patterns. And some have done the walking but wouldn’t do the counting. They’ve just eyeballed it—which tells you nothing! 

The equivalent of all this is big-game hunting without sighting in the rifle. Truly this is assumptive behavior that causes much wounding loss afield. The US Fish and Wildlife Service estimates that this loss amounts to several million birds annually, which takes a big bite out of the resource.

Assumption 3: It’s OK to shoot shotshells without knowing their pressure levels

Now right out of the chute factory loads, assuming they are the correct length for a given chamber, are fine, as unless misloaded they always develop pressure levels within SAAMI or CIP pressure standards by gauge and shell length. But this doesn’t mean they can’t be misused and create overpressure situations. 

An example would be shooting long shells in short chambers. Every shotgun (save some vintage guns) has a chamber length clearly defined in its owner’s manual and/or stamped into the barrel indicating the maximum length of shotshells of that gauge that can be safely fired in the barrel’s chamber. Exceed that length—say, shoot a 3" shell in a 2¾" chamber because it will fit—and you will always cause a pressure increase of 1,000 to 2,500 psi as the wad and shot try to jam through the ever-narrowing end of the chamber. The bigger the shot size and the higher the velocity level, the greater the pressure rise will be. The “bite” of this false assumption is to stress and loosen your shotgun, break internal parts, crack wood and beat you up with excess recoil. 

Another iteration of this bad assumption is shooting modern shotshells in vintage guns that were never designed for the pressure levels and quick-rise pressure peaks developed by today’s smokeless-powder loads. Many are the old shotguns that have been bulged, split or actually ruptured from this super-dangerous assumption. And trust me: From serving as an expert witness in personal-injury cases, this assumption can not only bite the gun, it can also bite your forehand or face with serious injury. Always know and never just assume the maximum pressure level that your shotgun can handle. 

To consult with Tom Roster or to order his new Advanced Lead & Bismuth Shot Handloading Manual, his current HEVI-Shot and HW-13 reloading manual, or custom loading data, contact Tom Roster, 1190 Lynnewood Blvd., Klamath Falls, OR 97601; 541-884-2974,

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