2 Chokes with S Nova

Pat's Notes from the Field: Shotgun Chokes for the 3Gunner

The 3-Gun shotgun is a versatile beast. Stationary steel and flying clays are no match for this Power Tool with the right load and choke. Distant targets can be bested with slugs. Given a good understanding of choke and pattern, bird shot can be used with precision on closely spaced shoot/no-shoot targets. Unfortunately much of what makes the shotgun so flexible leads to one of the reasons we fail to knock down targets we actually hit! I am talking about interchangeable choke tubes!

2 Chokes with S Nova

You will generally find me running a Light Modified choke unless I see an advantage to something else. Similarly my AR’s optic is on one power until there is a need for a change. But much like my optics, the benefit of variable chokes is in changing them to fit the target.

The ability to instantly change your pellet spreader’s shot pattern has been around for better than 40 years. Screw in choke tubes are now factory standard on all but the most basic models of shotgun. The fact that we have them however doesn’t equate to knowing how to use them. Read along and we will discuss how to harness the versatility and avoid the pitfalls of choke selection.

Let’s start with the most open choke pattern and move to the least or tightest pattern. We’ll cover the common units and some “specialty chokes” at the end. You’ll find the designations are for the most part self-explanatory.

Cylinder Bore (CYL) This choke is just an continuation of the barrel’s nominal bore diameter and is bored as a straight tube with parallel walls for the entire length. Makes sense right? From Cylinder Bore each successive choke tube “restricts” the barrel’s exit diameter to some degree. While each choke can be expressed numerically as .010” or .020” or .030” restriction from Cylinder Bore, those numbers are verbalized as Ten, Twenty and Thirty point chokes. I actually like using the Point System as it is an accurate description of what the heck you are screwing into the end of your shotgun. The English might use the terms like 1/4, 1/2 and 3/4 choke, but generally we colonists use names.

Skeet (SK) The first step in from Cylinder Bore at .005” restriction.

Improved Cylinder (IC) Is a 10 point choke or .010” tighter than Cylinder Bore. This is one of the most widely used chokes in 3-Gun.

Light Modified (LM) Adds another .005” of restriction for a total of .015” from the straight walled Cylinder Bore. If you aren’t sure what choke to use, or you don’t want to be bothered to change chokes, “Lt. Mod” is a great default choke. It works well in most any application.
Modified (Mod) This choke will have your pellets flowing though a exit hole .020” smaller in diameter than Cylinder Bore.

Improved Modified (IM) I bet you are seeing a pattern (gun pun intended) here. Yup, “I-Mod” will close the muzzle I.D. down another .005” for a total of .025” restriction.

Full (F) Is the tightest constriction among the standard chokes and is a full .035” narrower than Cylinder Bore. This is one I have yet to use at any 3-Gun event and hope to never feel the need too. If the target is that far away or that tough to put down, somebody hand me a carbine!

Beyond these, some aftermarket manufacturers have created chokes more “open” than Cylinder Bore: like Diffusers and Spreader chokes and chokes that are fuller than Full, with names like XtraFull, Turkey Full and Super Full (sounds like me after Thanksgiving dinner). With the possible exception of a Diffuser, we don’t have any real need for most of the other “speciality chokes” within the sport of 3-Gun, so I’ll not go into them.

choke chart

Hit and Miss

While you can find some nice choke selection information for shooting clays, it does not translate very well when the target is made of steel. So let’s create our own.

The standard load in 3-Gunning is a 1 1/8 ounce of shot at 1200 fps (3 dram). I used those made by Fiocchi loaded with 7.5 shot on three types of MGM steel targets: full size Poppers, 6” rounds and a Whirly Gig. In each case a perfect center shot was made and repeated several times to confirm the data. Other loads were tested and will be discussed later.

1 Whirley Plate 1

Cylinder choke was reliable to 25 yards on the Popper, and to 20 yards on the 6” plate. The Whirly Gig shortened the effective distance even further to just 15 yards.

Improved Cylinder was not able to improve the results of those shown by Cylinder.

Light Modified was able to improve the distance on Popper to 27 yards and the 6” plate to 25 yards. The Whirly’s plates gave up at 20 yards.

Modified put the Popper and the 6” plate down out to 30 yards. While the Whirly Gig gave up its targets out to 25 yards, it did so reluctantly.

6 Whirley 2

Improved Modified was able to stretch out the Popper to 35 yards. The 6” plate found the dirt at 30 yards but the Whirly held fast at that distance. Twenty-five yards is as far as one should go on the Whirly Gig to get solid drops.

Heavy Loads

I know a number of competitors that bring a box or handful of “High Brass” loads in case stubborn or distant targets are encountered. Do they work? Does the increase in recoil and the resultant increase in recovery time pay off? I got a surprise for you. Not only did I test some Heavy Field ammo, but I also got some great results with loads on the opposite end of the power curve! The short of it is...you are welcome to go heavy, I will just change chokes.

In testing, the heavy loads duplicated the results with the standard 3 gun load to about 25 yards. Modified choke was necessary to see any “real” difference beyond that. So that’s where we will start.

The Heavy Field load was a Winchester 1 1/4 ounce #5 shot at 1250 fps (3 3/4 dram).

While Modified Choke "popped"  Poppers down at 30 and 35 yards, but wouldn’t drop the little 6” plate beyond 25 yards and the Whirly Gig was not always compliant at 25 yards.

Improved Modified did the same with the Popper at 35, but still could not drop the 6” plate past 25. I did get a reliable release of the Whirly’s plates out to 25 yards.

After abusing my shoulder with the heavy stuff, I did some testing with some uber light loads. I found some Federal subsonic 1 1/8 ounce #7.5 shot 900 fps loads and ran the full test again.

Cylinder had the Popper and 6” plate falling to 20 yards and the Whirly at 15 yards.

Improved Cylinder provided no improvement.

3a Six inch Smacked

Light Modified sacked the Popper and Plate out to 25 yards and was OK but not great on the Whirly at 20.

Modified showed the Popper the way down to 30 yards, and the 6” plate at 25 yards, and was solid on the Whirly at 20.

Improved Modified put the Popper away at 35 yards, the 6” plate fell well at 30 and the Whirly gave up its plates, albeit reluctantly, to 25.

4 Popper Popped 1

There is a lot to like about these subsonic loads. They are easy on the shoulder, create less muzzle rise and very close in performance to the 3-Gun “standard” (1 1/8 @ 1200) loads. While I don’t think many self-loading shotguns will run them reliably, the pumpgunner in me loves them!

With rifle and pistol we are firing a single projectile no larger than half an inch in diameter. Our aiming error is limited to the size of the target plus half the diameter of the bullet. It works the same way for shotgun but our projectile is much bigger! These power tools are effectively sending a 10- to 20-inch flying “Lead Net” downrange. The idea is to select a choke and a load that will effectively put the target down with something less than the center of the pattern. This greater margin of error allows you to shoot faster, knocking down steel and breaking clays with your sights off the target! The reason we use a pellet-spreader is to take advantage of spreading those pellets!

You know I love to shoot fast. I mean who doesn’t like the feeling (and the sound) of blowing steel into the weeds. Or finishing up a “strafing run” across a set of stationary clays, each one giving up in a cloud of smoke! So go ahead, let-the-choke-out and you just might find that the shotgun is the most fun-gun in the game!

Slugs!  I did not cover slugs, but in short...standard "Foster" and "Breneke" style slugs can be shot through any choke up to and including FULL without cause or concern.  You will however find that the more open chokes yield the best accuracy.

Thank you for your time,

Patrick

Patrick E Kelley

2 comments

  1. Shane Zeppelin 17 February, 2016 at 02:00 Reply

    Great article, Pat! Thank you for doing all this work and sharing your results. It’s good to know that heavy loads can be “outgunned” by light loads by simply using your chokes.

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