Shot Size, Chokes & Patterning Your Shotgun

Once upon a time I just assumed that every shell and any choke combination would “work”. Not true.

I’m sure you’ve seen it on forums and FB groups but if you haven’t, I’ve lost count of “what shot size do I use for ‘x’ species” of bird?” or “Which choke/chokes do you run in your guns?”

More often than not, it’s folks stirring the pot and they’re probably sitting on their porch, drinking a beer and wanting some cheap entertainment by reading the comments as folks banter back and forth. 

While I’m not here to argue at all, I want to share my .02 on the subject and hope that if anything it’s thought provoking and lights a fire under your rear to do a little research and testing to arm yourself with the understanding and first hand experience of how your gun performs and provides the confidence to make the shots you know you should and be okay passing up the shots you shouldn’t take. 

So, while we won’t dive into the specifics of either of the mentioned two questions, we will dive into patterning your shotgun which as you’ll read below, will more than likely provide direction to both, within reason.

To clarify on what I mean by ‘within reason’, I’ll state that a combination of variables factor into shot size and choke choice, but a simple “this shot with this choke because that’s what someone on the internet said” isn’t doctrine.. Just because 'Joe Schmoe' can hit his 9 iron 200 yards doesn't mean everyone should use their 9 iron when they're 200 out from the flag.. make sense? Cool, let's keep rolling.

Have a Goal and Baseline Expectation for you Setup

To start, and build a baseline for the examples we’ll dive into, we’ll talk about my personal hunting desires and what I hope for in my gun/shell/choke performance.

For me, I hunt over pointing dogs and my average shot distance, that I'm confident taking and making, is inside of 40 yards.

That doesn’t mean I can’t shoot a bird beyond that distance, but for me I enjoy the rise of the birds and wild flushing or bumped birds aren’t birds I’d like to shoot.

To me, it’s not about it “happening” it’s about “how it happens”. That’s how I enjoy upland hunting and it doesn’t make any other way to enjoy it wrong, just my choice. A bird means nothing if it wasn't taken in a way that I was excited about. That’s just where I’m at in my upland hunting journey. 

So, with that context and goal in how I want to shoot birds, I have now set a standard of performance for my gun and how and at what distances I need my combination of shot size and choke combination to perform. That’s the first step.

Step 1 - Decide at what distances you want to shoot birds 

Let’s say I’m hoping that I’ll have birds blowing up at my feet and by the time I shoulder the gun, pick a bird from the covey, swing through and fire my shell.. I’d imagine that bird will likely be in the 20-30 yard range. If I'm fortunate to down a bird on my first shot and there’s a late flier or one just out front I can continue moving my barrel through the bird, which I’d imagine it’ll be 30-40 yards before my pattern is on the way.

So, I need to ensure that my choke and shot size combo are distributing a thorough and dense pattern at those distances..20-30 yards and 30-40 yards. I don’t want my pattern to be too tight that there’s no forgiveness or that it's no wide that there’s holes in my pattern that could result in a cripple or missed bird. I don’t need help missing as it is.. Lol

Lastly, Keep in mind, bird behavior changes throughout the season as they become wise to hunters and hunting pressure. Understand what birds do at different times of the year and change your shot and chokes as needed to accommodate the conditions and bird’s behavior.

Just because you shoot one combo early season doesn’t mean that’s optimal across the board for all species and all circumstances. It’s important to know how those shell / choke combos perform to make those decisions. Knowing that could make or break your hunt. I’d hate to go on a big trip without my gear bag and be battling jumpy late season birds that are constantly out of ethical range.

Information is power in the field and will help you be successful. You just have to know how everything works together.. which leads us to the next step.. Pattern your gun.

Step 2 - Pattern Shells with Choke Tube/Tubes

With the goal of shooting birds at certain distances, we’ll move to some basic shot size and choke understandings. Keep these 2 things in mind as you select your combination:

Shot Size 

Smaller shot size means more shot in the air and denser patterns. Smaller shot also means less mass weight per pellet and less energy at longer distances. The opposite holds true for larger shot sizes. Larger shot size means less shot in the air, but more energy at further distances, which equates to more ethical kills at longer distances. I use “down range” and “distance” subjectively to your desired results. To me, 40 yards isn't a far shot, it's just at the edge of where I'm okay saying, "well find another covey" and watching it fly away.

With my standards being inside of 40 yards, I’ve found that 6’s and 7.5s give me the most desirable consistent patterns, forgiveness in pattern spread and higher hit counts to fall birds and improve recovery. 

For example, on average a 1oz load (which is about as heavy as I shoot out of my 20 or 28’s) of 7.5s gives you roughly 345 pellets. The same 1 oz of shot weight in 6’s is 232 pellets and in 5’s is 172.

In comparison, 7.5’s yield 32% more pellets vs. 6’s and a whopping 50% more than 5’s. Keep this in mind as we continue below as it's important to understand why I shoot these shot sizes.

So, which shot size do I use to deliver an ethical kill? That boils down to some simple math that helps us calculate momentum and kinetic energy. The two key ingredients to a quick, humane kill.

In speaking to these two calculations we have to consider the total amount of energy and momentum that can be created by a multitude of impacts. Because we’re not talking about rifles here, we’re talking about scatter guns. 

I’m aware a single number 5 shot will deliver more energy and penetration vs a single 7.5. But again, we’re not talking single projectiles here, we’re talking about total accumulated energy from multiple impacts and total amount of penetration.

Let’s break it down.. 

The formula for momentum, which attributes to “stopping power” is -Momentum = Mass x Velocity

We'll use the following data in this formula.

• 7.5 single pellet = .003 oz (This is 1 oz of shot divided by 350 pellets of 7.5s)
• 5 single pellet = .005 oz (This is 1 oz of shot divided by the 170 pellets of 5’s)

Assuming an average of 636 fps of a 7.5 pellet at 40 yards (based of ballistics that are sourced at the end of the article) we can calculate a single pellet’s performance. Note - a #5 pellet will be moving slower at 40 yards due to it's mass weight. For the sake of the example, we're letting the #5 cheat a little bit.

• 7.5 Pellet // .003 oz x 636 fps = 0.391 lb.fts energy per #7.5 pellet

• 5 pellet // .005 oz x 636 fps = 0.652 lb.fts energy per #5 pellet

If it’s apples to apples and we say 50% of a 1oz load, in either shot size, hits their mark @ 30 yards, the total energy delivered from each load would be:

• 0.391 of energy per 7.5 pellet x 170 (half of the 350 that are in 1 oz of 7.5s) = 66.47 lb.ft
• 0.652 of energy per 5 pellet x 85 (half of 170 which are in 1 oz of 5s) = 55.42 lb.ft

That’s over 11 lb.ft advantage to the 7.5s.. And that’s assuming that it’s an apples to apples ‘hit ratio’, when in reality the likelihood of a higher percentage of hits with the 7.5’s is realistic due to the 50% in pellet count that’s in the air. 

If you want to calculate kinetic energy, you’ll still see the advantage go to 7.5s.

It’s a volume play and to me personally. Volume creates forgiveness in pattern to help give me some wiggle room on my shooting, while also totaling a higher delivery of both KE and Momentum when I get a hit.

I’ve shot ample wild pheasants and sage grouse with 7.5s from a 28 gauge. It’s no joke on the big birds that take more hits, because they’re bigger bodies, and again is forgiving on smaller birds, like chukar and quail, where the shot density helps knock them down harder.

Now before any torches and pitch forks come out, I am NOT saying that 7.5s are the do all for every upland application. I shoot 6’s quite often as the season progresses. What I am saying is that at the distances I am shooting wild birds, my test results, and the numbers, make a TON of sense.

Do your homework and make sure you find the right shot size for your hunting goals and circumstances. The only way to know for absolute is to go pattern your gun. Every gun, shell brand and choke combo will yield different results. 

Choke Selection

To save some writing, this is a great graph with all the data required to give you a starting point. This is sourced and credited to shotgunworld.com:

Referencing this graph, again keeping in mind your desired distance you’ll be shooting birds at, you’ll note some very important information that will give you an idea of which chokes to pattern with your shells. Remember, these numbers are general and not set in stone. You have to test.

Again using my personal ideal shot distances 20-30 and 30-40 yards, a cylinder and I/C choke give me some great pattern width and forgiveness. I just need to ensure that the pattern density is sufficient to deliver a clean kill. So, that’s where I would start with my testing to confirm if that's right for me or not.. Time to shoot.

Step 3 - Test and Pattern

To start, I’d shoot my CYL choke at 20, 30 & 40 Yards and gauge the results. I’d then repeat the same steps with my IC choke and collect the data. If I was testing 7.5’s vs 6’s or 6’s vs 5’s, I’d shoot the other shot sizes as well.

Upon completing shooting each choke and the particular shot size I’m testing, I’m going to look for 2 things on the paper patterns I’ve shot:

1 - How dense is the pattern? Are there gaps or holes in my pattern and at these specific distances will I deliver enough hits on a bird to ethically and humanely kill it?

2 - At what distance does this choke/shell combo’s efficiency fall off and not deliver the pattern density or results that meet my expectations?

With this data you have built a baseline to compare additional results to and additional testing is required to ensure you find the right combo.

You can now test to your heart's desire and find which combination of equipment meets your goals and expectations.

Summary

I’d highly recommend testing different brands of shells, shot sizes and choke combos until you find the right combination that provides the desired results you’re confident in.

I believe the birds we hunt deserve our best and I’d invite you to put in the time not only finding the right combo of shells / chokes but spending time at the range and brushing up on your shooting.

Upland hunting isn’t about shooting limits or stacking birds, but it is fun to put one in the bag now and then. Put in the time and you’ll reap the rewards. 

Safe shooting and hunting, friends. God Bless.

Matt Davis / Founder

Sources:

- Shot Size / Choke Tube Data and General Recommendations - https://www.shotgunworld.com/threads/shotgun-ammo-and-more-shotgun-ammo-shotgunworld-com-is-your-best-source-for-shotgun-info-on-shotgun-ammo.537437/ 

- Ballistic Data Testing - https://rangeservices.nra.org/media/4074/shotshell-ballistics.pdf 

- Kenetic Energy & Momentum Calculator - https://www.calculatorsoup.com/calculators/physics/kinetic.php