Aftermarket Chokes

Hi Bruce,

I have shot for 10 years and your writings have convinced me to change my shooting habits. I now enjoy sporting clays and 5-stand and skeet much more now. The reason is that I have been shooting Marocchi Conquista’s and getting the heck thumped out of me, I started to shoot the Lanber 533 semi-autos and have not shot the Marocchi since.

Recently here in Houston Texas I saw the Beretta AL 390 Silver Mallard 30 inch field on a closeout for $537.00 so I bought two. My question is this, Everyone is telling me to throw the Beretta factory chokes away and get Briley’s here in Houston. Guys I shoot with claim that Beretta is the worst in holding tolerances on their chokes.

So far I have been happy with my patterns from my stock of Estate ammo sporting loads. Since I am new to owning a Beretta is there a problem with their choke tolerances and is there a good chance that Briley tubes will provide superior patterning. I don’t want to go out and spend $100.00 or more for new chokes to find out that my Beretta tubes are fine.

Bruce, what information or opinion can you offer regarding this issue? Thanks and I do look forward to your response! Thanks again for helping me see the light with the 390 vs O/U’s I shoot more now than ever and have more fun doing it!

Best Regards,


Dear Greg,

I have to keep on saying this until I am blue in the face- the ONLY way to know what kind of patterns your chokes produce is to actually go out and pattern them with the shell of your choice! You can’t just buy a choke that is stamped with a designation or measures a certain amount and be sure that it will produce a certain pattern with a certain shell. Life just isn’t that simple, in spite of what the aftermarket choke makers tell you.

Here’s a question for you: If a choked is marked “Modified”, but it measures .030″ constriction and throws a 50% pattern with a certain shell, is that choke Improved Cylinder, Modified or Improved Modified?

By simply switching from Remington STS loads to Remington Gun Club loads I can immediately open my pattern from 75% to 63% when using a certain choke. What would I call that choke?

A popular way of naming chokes in the US is to do it by constriction. Here’s the more or less currently accepted list:

.000″ Cylinder Bore
.005″ Skeet or Skeet 1
.010″ Improved Cylinder
.015″ Light Modified or Skeet 2
.020″ Modified
.025″ Improved Modified
.030″ Light Full
.035″ Full
.040″ Extra Full

Of course, this list was put together by the vendors of choke tubes. Note the convenient name for every possible .005″ increment. That’s good for business. In an ideal world, each .005″ would give you another 5% pattern density. If you started with Cylinder Bore giving a 40% pattern and Extra Full producing 80% (40 yards) it works out nicely.

Of course, the real world is a little sloppier than that. If you shoot a box of shells through a Modified choke and get an average pattern of 60%, don’t be at all surprised if the extreme spread of those 25 patterns would range from 55% to 65%. According to Browning’s web site FAQs, shooting a 2-3/4″ target shell in a 3″ chamber gives a potential for a 45% to 65% variation under the same conditions.

I’ve heard a number of people comment that Beretta’s choke constrictions were “way off”. I have a couple of 303s with the original Mobilchokes. Mine are all within .001″ of the nominal designation as listed above. When I bought additional Mobilchokes I just kept miking them as I rooted through the dealer’s shelves and picked the ones that were dead on. When I tested a recent 682 E Optima Bore, I found the Cylinder choke to be plus .004″, Skeet +.002″, IC dead on at .010″, Mod was light at .016″ and the Improved Mod was sort of on at .028″. For the truly anal retentive, this may not be close enough.

The chokes that are really off, when you go by measurement only, are the Browning Invector Plus chokes. The skeet was .002″, the IC was .004″ and the Improved Modified was .020″. I also reviewed a Browning Gold auto with an IC of .004″, Modified of .012″ and a Full of .030″.

I really can’t say whether aftermarket chokes will or won’t provide superior patterns. What is a superior pattern? If it’s just tighter, then just use more squeeze. If you can get a 60% pattern from .010″ constriction, is that any better than getting 60% from .030″ constriction? Maybe. Maybe not.

In THEORY, the less squeeze you use to get a given pattern, the less pellet deformation you will sustain. Of course, pellets get deformed in places other than the choke. Look at Brownings short forcing cones, but big bore. Look at Beretta’s fairly long stock cones and tight bores. Bet you didn’t know that Berettas already came with pretty long cones, did you. Measure them and see for yourself. I can’t tell you how many shooters I’ve talked to who have had their Berettas cones “lengthened” and never bothered to measure what comes in the gun originally. Roster says that anything much more than 1-3/4″ is a waste, even with large shot. Beretta’s stock cones are close to that.

What custom chokes and custom installations can do for you is to minimize the step between the rear of the choke and the bore. To avoid a problem with “ganging of tolerances”, most factory screw chokes have a large drop from the bore to the rear of the skirt “just to be safe”. I’ve seen drops as much as .050″. That kind of bump can’t be good for the shot. Teague custom installation from England have almost no visible drop. There is no way a screw choke can equal the performance of a solid choke especially in the tighter constrictions, but the less drop the better.

Also a good custom installation can ensure concentricity. Not only concentricity of the threading, but also of the tube itself. Remington has been having a bad run of incorrectly installed chokes. Of course, all you have to do to test concentricity is pattern your gun. You’ll find out soon enough if you have a problem.

Custom chokes can be had in the extended versions. This can be a plus depending on how the custom shop designs the interior of the choke. A longer chokes gives them more options. Unfortunately, the problem with most screw chokes is that they are all the same length from cylinder bore to full. Optimally, the tighter the choke, the longer the choke forcing cone and parallel section should be. You can’t do that with most screw chokes (though Fabarms does offer screw chokes of different lengths). That’s why the best trap and pigeon shooters still use solid chokes, not screw-ins.

And then there’s shot string. It’s often said that the difference between a good patterning choke and a poor one is the length of the shot string. Abused pellets tend to string out. Coddled pellets less so. Unfortunately, it takes some pretty sophisticated testing equipment to test shot string properly the way Roger Giblin did in England or the adventurous Brister did in Texas. I don’t have it and neither do you. And neither do those custom choke shops. So let’s not talk shot string. If you think that you can guesstimate shot string from watching target impacts, you’re a better man than I.

Bottom line: Do you get better patterns with aftermarket chokes? Dunno. What kind of patterns are you getting now? What! You haven’t done the work? You haven’t devoted weekend after weekend to counting tiny little holes in paper? You say you have a real life? Then you are going to have to cut corners and take things on faith, not fact.

I suggest getting the aftermarket chokes that come in the prettiest colors.

Best regards,

Bruce Buck
The Technoid writing for Shotgun Report, LLC
(Often in error. Never in doubt.)

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3 Responses to Aftermarket Chokes

  1. Out of interest to the subject here is a table from measurements of my Caesar Guerini Magnus Grouse Sporter. Maxixs choke tubes

    The left column is the general ‘industry spec’ as nominated by some aftermarket choke manufacturers and to my way of thinking is a reasonable standard to measure from.

    The right column is the true miked diameter of the choke. Way off mark but what I do to compensate is to simply use one choke tighter than actual. Pattern testing suggests the actual is pretty much spot on.
    Hey it works for me, the targets get crunched very well!

    Top Barrel ID actual 0.732
    Bottom Barrel ID actual 0.731

    Cyl – (.000) -0.002 under Cyl

    Skt – (.005) 0.003

    IC – (.010) 0.007

    Lt Mod – (.015) 0.011

    Mod – (.020) 0.015

    Imp Mod – (.025) 0.021

    Lt Full – (.030) 0.027

    Full – (.040) 0.032


  2. jim rennie says:

    Yup, screw-in chokes and aftermarket chokes require a LOT of pattern testing to find out what is really going on. Bruce is correct in his analysis of the Browning invector plus chokes,as they are much more open than stated. Once you realize this and pattern test, it’s not so bad, and it’s possible to select the correct choke tube. Browning makes things even more confusing with their extended choke tubes that measure a different restriction than the flush fit tubes. One nice thing about the Invector Plus tubes in the overbored barrel is that they fit with no step between the bore and the choke. At least that’s the way it is in my gun.. My Weatherby SA 08 on the other hand is a slimbore gun and has a very noticeable step from bore to choke tube. Jim.


  3. I want a choke with a big window. I want a choke I can shoot station 8 and station 4 in a windy area and also bob white quail with out changing chokes. I have a Browning Maxus that the difference in the barrel and Carlson skeet is .0085. Big drop off at the choke inlet .748 plastic build up begins inside the choke a ways. Excellent pattern at 25 yds. with hard shot well distributed inside 24 inches. Gun Clubs will give you flyers that would not even be on the paper at 30 yds. My Benelli M2 will shoot this pattern with a Muller U1. Shot alot of quail with this choke again hard shot. Gun Clubs the pattern will be as big as a barn with flyers. Gerald


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