Shotgun Patterning

What is it and why it's important - By Craig Endicott

There are a lot of differing opinions about what works and what doesn’t work when it comes to nontoxic shot loads and their effectiveness for waterfowl hunting.  Hunters don’t want to have to get a degree in physics to understand why this or that works, they just want to know what does work! 

Well, there’s no getting around it, if you really want to know what your gun/load/choke combo is capable of, then you’ll need to pattern test it to find out.  It isn’t a complicated process, but it does take some time and effort. 

Why should I pattern test my shotgun? 

Patterning your shotgun provides you with valuable information on the performance of your gun/load/choke combo.  This information will allow you to make informed choices on your load, choke and pellet selections to match your particular hunting/shooting situation.  Ultimately, patterning and tailoring your combo will improve your effectiveness as a hunter by reducing the number of shots you’ll need to get your birds and reducing crippling in the process. 

Hunting time and opportunities at game are too precious to just go with an in-the-field trial-and-error method.  Pattern testing, if done properly, will allow you to take the guesswork out of selecting an effective combo for your hunting. 

How do I pattern test my shotgun? 

1.         Find a location that has an adequate and safe back-fall area.  Don’t forget, you’ll want to bring both ear and eye protection. 

2.         Set up a pattern board so you can attach pattern sheets.  One quick and easy way to do this is to put two posts in the ground about four feet apart and attach a 4-foot x 4-foot backboard of cardboard, thin plywood or black particle board to the posts. 

3.         Get some 40-inch x 40-inch (minimum) sheets of paper or cardboard.  Try to locate 48-inch wide rolls of white paper at industrial supply or paper warehouses.  It also saves time at the range if you precut this paper into pattern sheets. 

4.         Measure off your maximum shooting distance from muzzle to target with a measuring tape. 

5.         Attach a blank pattern sheet (a staple gun is handy) to the pattern board and fire one shot at the sheet.  Remove the pattern sheet and repeat the process.  You don’t need to shoot these patterns from a bench, just shoot at the center of the sheet to get them on the paper. 

6.         Shoot a minimum of three patterns for an average and five is better. 

7.         After shooting, draw a 30-inch diameter circle using a 15-inch string and pencil or a yard stick with holes 15 inches apart to scribe a circle that encompasses the densest portion of the pattern. 

8.         Count the pellet strikes inside or on the 30-inch circle and average the pattern count.  You can calculate a pattern percentage if you like, but you don’t need to.


How do I know if a pattern is effective? 

In order for a pattern to be effective it must possess sufficient pattern density to reliably hit the vital areas (brain, spinal cord, heart or lungs) of the target bird and contain pellets capable of delivering adequate energy to penetrate those vitals areas at the ranges you shoot your birds. 

It’s important that you understand how these two parameters will ultimately determine your combo’s capabilities. 

Sufficient Pattern Density -- enough pellets in the 30-inch diameter pattern circle to reliably hit the bird’s vital areas.  This pattern density or minimum pattern count is determined primarily by target bird size.  Your combo will need to meet or exceed the minimum pattern count regardless of the yardage to the target bird.  It doesn’t matter if a mallard is at 20 yards or 50 yards, the minimum pattern count necessary to kill it is the same.  That’s because the mallard is the same size relative to the 30-inch pattern regardless of the distance.  Granted, the mallard and pattern look much smaller at 50 yards than 20 yards, but the mallard is still the same size relative to the pattern regardless of the yardage.  As a side note, as range increases it can become more difficult for a combo to meet the minimum pattern count, but that’s another subject to be covered later.

 Adequate Pellet Energy -- pellets possessing ample per-pellet energy enabling them to penetrate the bird’s vital areas.  The minimum amount of pellet energy needed to handle this task is primarily determined by the distance from shooter to bird and bird size while the amount of energy a pellet carries is determined by its mass, size, velocity, shape, etc.  All pellets (regardless of the metal type, size, etc.) have a distance at which they no longer possess adequate penetrating energy for a given bird type and size.  Beyond that distance, one of the easiest ways to increase pellet energy and maintain the minimum threshold is to move to progressively larger pellets. 

How do I assess my pattern results?

Now that you are familiar with what it takes for a pattern to be effective, you’ll want to compare your combo’s patterns against reliable information to assess their capabilities.  To date, the largest set of empirically tested lethality data on waterfowl and upland game birds is analyzed and presented in Tom Roster’s Cooperative North American Shotgunning Education Program (CONSEP) 2006 Nontoxic Shot Lethality Table (Copywrite 2006 by Tom Roster).  This table provides a wealth of information useful to hunters trying to sort through the myriad of nontoxic shot loads available today.  It’s a no-nonsense approach at establishing the most effective shot sizes, minimum load weights and minimum pattern counts necessary for clean kills on various body sizes of waterfowl and upland game birds. 

The table (available in the latest version of the Oklahoma Waterfowl Hunting Guide booklet) is Mr. Roster’s analysis of extensive terminal ballistics data derived from over 23,000 one-shot kills on waterfowl and upland birds.  This data was collected under actual hunting conditions with a trained observer present to record the many variables involved including: distance to the bird, angle of flight relative to the shooter, hits, misses, birds hit but not retrieved, load code (e.g., these were double-blind test where neither observer nor hunter knew what the load contained) and choke used.  All birds collected were tagged with identification information and frozen for a postmortem examination that included: x-raying in two planes (anterior-posterior and left-lateral), locating all pellet strikes, determining depth of penetration or pass-through for each pellet strike, as well as identifying any previous shot-in (carried) pellets and/or ingested pellets.  The test loads were also patterned through various choke constrictions and at a range of distances to establish pattern densities. 

What if I don’t know which load or choke to try? 

First, you’ll need to answer a few simple questions about your hunting/shooting situation.  What kind and size of birds do you normally hunt and what is the maximum distance you usually shoot your birds?  Once you have answered those two questions you then refer to Roster’s CONSEP table to see which activity and typical shooting range your hunting falls into and then see what the most effective nontoxic shot sizes are, what the minimum load weight is, and what the suggested starting point is for your choke.  All that’s left now is for you to gather the appropriate loads and chokes and head to the range for some pattern testing.

 What do I do with my pattern numbers? 

Well, what’s the average pattern count your combo put in the 30-inch pattern at your maximum shooting distance?   Let’s go back and refer to Roster’s CONSEP table to see if your combo’s pattern count can meet or exceeded the minimum pattern count listed for your type of hunting.  If it does, and you are using one of the appropriate shot types and sizes listed for the bird size and you keep your shots within the range of the activity, then you are good to go.  You can feel confident that any bird of that type/size and at that distance or closer will be in the bag if you do your part and put the pattern on the front end of the bird.

If your combo doesn’t meet the minimum pattern count then there are a few things you can try to improve performance including:

- reducing your maximum shooting distance

- trying different (usually tighter) chokes

- trying other shot sizes listed for the activity

- trying different load weights or velocities

- trying different brands of ammunition 

If your combo’s pattern count is considerably higher than the minimum and if most of the pellet strikes are concentrated in the center core of the pattern then there are a few things you can do to try and “open-up” the pattern (making hitting easier) while still not falling below the minimum pattern count including:

- trying different (usually more open) chokes

- trying different shot sizes listed for the activity

- trying different load weights or velocities

- trying different brands of ammunition 

Other important points to consider 

What about calculating pattern percentage, isn’t that what I really need to know?  Well, you can calculate your combo’s pattern percentage (I usually do), but it isn’t necessary.  Pattern percentages are mostly indicators of load and choke efficiency.  They don’t really tell you anything about how effective your combo will be at harvesting birds. 

Now, if you want to know if your load and choke combination is performing up to industry standards, then by all means pattern your combo at 40 yards (muzzle to pattern), use a 30-inch diameter circle (the standard distance for all gauges except the .410 bore which is 25 yards and a 20-inch diameter circle) and calculate the pattern percentage.  Compare your results against the manufacturer’s choke table and you will know if your combo is performing properly.  Remember, if you want this to be a true load and choke evaluation, you will need to open and count the pellets in a minimum of three shells to use in your percentage calculation. 

Isn’t all patterning supposed to be done at 40 yards?  Not really, if you want to know what a particular combo is doing at any given yardage then you will need to pattern it at that yardage.  Of course, there’s nothing wrong with patterning at the standard 40 yards if you are looking for a good combo at that distance, but let’s say you want to find a good 30 yard teal combo or a 50 yard goose combo.  You would then need to pattern some combos at those ranges to evaluate them.  There are no shortcuts for this, you can’t just pattern at 40 yards and then look at a chart and expect this or that percentage at this or that yardage. 

What about uneven patterns or patterns with holes?  All patterns have some pellet clustering and pellet free areas, but don’t be overly concerned about them as long as they don’t dominate the overall pattern picture.  Common sense tells us to select combos that exhibit good pellet distributed so if one combo gives more consistent or better pellet distribution than another, as long as it meets the minimum pattern count, go with it. 

Don’t confuse this pattern testing with checking your gun’s Point-of-Aim (POA) and Point-of-Impact (POI).  In these exercises, you are checking to see if your gun shoots where you look/point, mostly a gun fit issue.  This pattern testing is designed to evaluate your gun/load/choke combo’s performance, not your ability to center a pattern in a pre-drawn 30-inch circle!  Shotguns don’t always shoot to the same POI each and every shot, even if they are shot from a bench.  That’s why you scribe the 30-inch diameter circle encompassing the densest portion of the pattern spread after you shoot the pattern, not before.  Now, you may get some indications of possible POA/POI issues while doing this pattern testing, but you can address those later. 

Lastly, work on your wing-shooting skills to become a more proficient shooter.  Shooting is an athletic endeavor so get with a good shooting coach, learn proper form and fundamentals, and then practice on clay targets that simulate your hunting/shooting situations during the off season.  It will pay big dividends towards your bagging success come next season.  After all, if you can’t put the pattern on the front end of the duck then little else matters! 

See the attached pattern photos to get an idea of what you will see when patterning.  These patterns are the results from: 1) the average pattern from a 5-shot string, 2) a distance taped from muzzle to target, 3) a post-shot scribed 30-inch circle around the densest portion of the shot swarm, and 4) an in-shell pellet count from the average of five shells.  In addition, they were shot on 48-inch x 48-inch pattern paper that has been trimmed down after the shot for storage purposes. 

One pattern pictured is a 12-gauge 2 ¾-inch 1 1/8-ounce load of #4 steel shot (average 218 in-shell pellets) at a velocity of 1,375 feet-per-second from a Remington 870 with a 28-inch barrel and a factory flush modified (.016-inch constriction) Rem-Choke.  The combo’s average pattern count was 150 pellet strikes so according to Roster’s CONSEP table it is capable of harvesting all duck sizes out to the 40 yard mark, but its relatively high pattern count would make it particularly effective on small or medium sized ducks. 

Another pattern shown is a 12-gauge 2 ¾-inch 1 1/8-ounce load of #2 steel shot (average 139 in-shell pellets) at a velocity of 1,375 feet-per-second from the same Remington 870 with a 28-inch barrel and a factory flush modified (.016-inch constriction) Rem-Choke.  This combo’s pattern count averaged 109 pellet strikes so according to Roster’s CONSEP table it proved it would be very good when shooting large ducks, pheasants and even small or medium geese out to the 40 yard mark.  However, the relatively low pattern count does not make it a good choice for small or medium ducks at this distance.


Pattern, 12 ga 1.125 #2 Steel M 40yd Pattern, 12 ga 1.125 #4 Steel M 40yd