Muller Chokes and the Mysterious Ü

Visit the Muller Chokes web site and you’ll see choke constrictions new to the shotgunner’s vocabulary. For example, Muller Choke constrictions are marked Ü1, Ü2, Ü3 instead of Skeet, Improved Cylinder and Modified. That’s because Muller Chokes does not believe in generic constrictions. One size does not fit all. Check it out:

Muller Ü0 = Cylinder/Skeet

Muller Ü1 = Skeet/Improved Cylinder

Muller Ü2 = Light Modified/Modified


Muller Ü3 = Modified/Improved Modified

Muller Ü4 = Full/XFull

Muller 4
The game-changing constriction identifications on the advanced Muller Chokes.

The reason I named my constrictions differently than the typical choke manufacturer is because a high percentage of the chokes you buy do not shoot the patterns that are marked based on the choke itself. I talked about this widespread problem in my last Shotgun Life article in regards to different guns and different barrels, such as bore diameters, metallurgy, machining and heat treatment.

Every Muller Choke has its own specific internal and external geometries based on how each and every gun make and model patterns best. Basically, in a nut shell, I changed every geometry in and on a choke until that particular gun model shot the most even pellet distribution patterns with lowest shot to shot deviation possible. 

When I accomplished that perfect geometry for that particular model gun, I drew the blueprint and went to the next gun make and model and started all over. So my chokes have different exit diameters, different internal and external geometries based on how THAT gun performed best with all different ammunitions across the board.

I did this through 20 guns, 13 different bore diameters and every ammunition on the market.  It took me 2½ years of pattern testing, high speed photography, shooting clay targets, live birds, paper, mud, water, ballistic gel, moving trailer with paper to observe shot string affects, wind testing to examine how shot patterns were affected with all shot sizes, payloads, velocities and materials.

All shotguns shoot differently. I discovered through my testing that if you put .020” constriction from the bore of a particular gun that does NOT mean it will throw a Modified pattern. That is such nonsense actually if you just stop and think about it. Take a .720 diameter bore barrel and put .020” constriction in it. What is the exit diameter? .720 – .020 = .700”

Now take a .745 bore diameter barrel and put .020” constriction in it. What is the exit diameter? .745 – .020 = .725”.

Jimmy Muller

So just based on this simple math, how can one say they are both Modified? They are obviously not! As a matter of fact, neither of these guns will shoot a Modified pellet count pattern. Then, take into consideration all the other physics and metallurgy and machining and geometries and now you have no idea of what pattern a particular choke is going to give you. So…I fixed all of those “unknowns” using my Gun Specific Patterning Geometry (G.S.P.G.) for each and every gun that accepts a Muller Choke.  

I started with my Featherlite Competition Series, then also with my newer Stainless Steel Competition and ultimately again with my newest H2O Waterfowl/Hunting Series.

Muller waterfowl
Muller Featherlite Chokes in Ü0 and Ü2 constrictions.

The question I often get is: Why did I designate my constrictions differently than everyone else? Because the old system is misleading and downright false. So why would I copy an age-old system that is wrong and obsolete at best? The answer is: I wouldn’t.

It’s the rigorous research and development underlying Muller Chokes that forced me to rethink the everyday constriction designations you’ll find from nearly every choke manufacturer. Since Muller Chokes performs differently, we needed to create a new choke constriction nomenclature. 

With my constriction designations and distances that I specify, you simply get the results that are specified and not “something else.”

The reason I laser engrave the designations into the ceramic is so it will always be there bright and white for easy reading at a glance. The reasons I made the chokes black is so the contrast of constriction markings it at its highest and also because I feel the black really compliments the guns beauty rather than gaudy colors that make the gun look cheap.

In regards to my H2O Waterfowl/Hunting Series Chokes, I named the constrictions to pertain to Waterfowl Hunters primarily.  Although these can be used for ALL types of Target Shooting and Hunting and 3-Gun.


The three constrictions for this series are as follows:

DECOY: For shooting over Decoys or decoying birds, approximately out to30 yards *.

PASSING: For Passing shots when birds are outside the decoy spread or at distances out to approximately 45 yards *.

ÜFO: For shooting beyond the Outer Limits, when shooting Tungsten Heavy Weight 13, 15, 18 cc/g or Hevi Shot or Bismuth or lead. This choke is capable of clean kills with the proper ammo beyond 60 yards * which is why it is a superb Turkey Choke as well. This choke can be used with steel shot if someone wishes to have extremely tight patterns at closer distances, but for extended yardages, steel shot energy per pellet drops off quickly and cannot retain enough per pellet energy to humanely kill live birds in most cases.

Most shotgun shooters forget that, even today, we are defining choke patterns from the 1940s and 1950s and that still applies to the popular chokes that you’re buying today.

*Distances are “approximate” because it all depends on the ammunition you are using. Pellet material, payload, velocity and quality all play into the actual killing distances as well as an individual’s wing shooting capabilities.

Jimmy Muller is Inventor and Founder of Muller Chokes. He’s an NSCA Master Class shooter FITASC, Sporting Clay and 5-Stand Competitor. Find out more about the extraordinary Muller Chokes at

Muller Waterfowl 5


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