The Truth About Frozen Shotgun Chokes

George Trulock of Trulock Chokes writes:

I’m sure a lot of shotgun shooters have encountered this dreaded problem. You start to remove the choke from your shotgun and it will not budge. You increase the pressure on your choke wrench and still get no movement. You eventually end up putting enough torque on the wrench that it causes your face to turn red and your arms too start to tremble. The choke still does not move.

You then find some sort of tool to give you additional leverage on the wrench and the darn choke tube still refuses to budge. You start to wonder what you did to cause this problem!!

There are basically three things that will freeze shotgun chokes in the barrel.

·        Rust

·        Residue build up from fired shells (unburned powder, fiber, plastic, etc.)

·        Choke tube expansion (Creep)

If you want to keep your shotgun chokes functioning as they were intended then the below maintenance items should be followed on a regular basis.

1.     Loosen and retighten the choke on occasion. Even better if you remove the choke and reinstall in the barrel on a regular basis. This will break any bond that is attempting to form.

2.     Clean the choke body and remove residue from the threads with a stiff brush and solvent of some kind.

3.     Clean the internal threads and choke counterbore in the barrel using a bronze bore brush and solvent.

4.     Wipe all surfaces dry after cleaning and lubricate them with a few drops of high quality gun oil.

Stuck Choke Tubes From the Use of Steel Shot

Choke tubes frozen in place from expansion is different from rust or residue build up. However rust, residue build up and choke expansion can all occur at the same time.

Without getting to deeply involved in the science of metals you need to know that when a shot charge passes through a choke tube it exerts a force in two different directions. Force is applied to the choke tube when the shot charge strikes the choke forcing cone. This is not how you want to remove a frozen choke tube.

Do NOT remove a choke tube suing this method

The first direction is longitudinal. The force in this direction simply tries to push the choke out of the barrel. This is prevented from happening by the interlocked threads on both the choke and the internal threads of the barrel. If enough force is exerted then the threads in the barrel and or the threads on the choke shear and out it goes. I have never seen a choke fail from thread shear.

The second direction is at approximately right angles to the bore. In this direction the applied force tries to make the choke expand. As the shot column moves through the choke tube forcing cone, the pellets are in constant movement to rearrange themselves so that the shot column becomes smaller in diameter and elongated. This generates a force that wants to expand the choke tube.

* Steel is elastic to some degree.

* If enough force is applied the choke tube will expand by a small amount and when the force is removed it will contract to its original size and shape.

* One of the ways we measure the strength of steel is by “Yield Strength”.

* For our purpose we can define yield strength as the maximum amount of force that is applied that does not cause any permanent deformation of the steel.

* If we increase the level of force past the yield strength of the steel used in that choke, it will expand past its elastic limit and stay in this expanded size.

*  If you continue to shoot this load in this choke tube it will expand a small amount each time and at some point it will be solidly locked into the barrel.

* This force reaches its peak nominally at the intersection of the choke forcing cone and the parallel section. This is the area where choke expansion will occur.

* Choke tubes in this condition cannot be removed by normal methods.

The actual force is generated from a number of combined factors.

1. Size of steel shot- The larger the diameter of the shot the more force is created

2. Weight of the shot charge- Heavier payloads cause higher forces

3. Choke constriction- More constriction causes higher forces

4. Velocity- the higher the velocity the more force is created

Very high velocity steel shot shells with large diameter (particularly size B and larger pellets) through tighter (typically full or tighter) constriction chokes are usually the culprit causing choke expansion.

One of the best ways to prevent choke expansion is to follow the choke manufacturer’s recommendations.

* Some choke manufacturers will mark the choke “no steel” if it is not rated for steel.

* Some mark the choke “approved for steel”

* All factory chokes, as a rule, are rated for steel shot loads from cylinder bore through modified constriction, at least all that I have seen.

* If you use a factory choke tighter than modified that is not marked for use with steel, I would check it on a regular basis for choke expansion.

* If you find a choke tube that gets progressively harder to remove and replace each time you do so, examine it carefully as it is probably failing from expansion.

* If in doubt whether a choke is rated for steel, contact the manufacturer

In my experience with steel shot I have found that if a choke does not expand with a given steel load after 25 shots it will never expand. Don’t take that as a fact as nothing is 100% when it comes to shotguns. However to date, this rule of thumb has never failed me.

comments

  1. avatar Anon says:

    If I have to use a cheater bar to possibly remove my choke I’m getting a smith involved or buying a new barrel

  2. avatar Ranger Rick says:

    “Wipe all surfaces dry after cleaning and lubricate them with a few drops of high quality gun oil.”

    So use of an anti sieze lubricant is now not recommend to prevent the “seizing” of a choke tube?

    1. avatar johnny go lightly says:

      Thinking the exact same thing.

    2. avatar uncommon_sense says:

      Uh, the author recommended that you add oil to your choke’s threads before installing it. Last I checked, oil is a lubricant. And oil prevents rust which is a main cause for choke tubes seizing in a barrel. Ergo, if someone tells you to apply oil to your choke’s threads before installing it, they are indeed telling you to apply an anti-seizing lubricant.

      Perhaps you were thinking of an anti-seizing lubricant with the consistency of grease rather than the consistency of oil?

      1. avatar raz-0 says:

        Perhaps they meant an anti-seizing lubricant that is designed as such, and thus has a component that is not a volatile organic compound that contributes to said anti-seizing properties.

        I’ve never seen a straight up oil ever referred to as anti-sieze compound by manufacturers who make such things. There’s a reason for that.

    3. avatar BLoving says:

      Nah, that just seems like an oversight here; of course it’s a good idea.
      I think the main point was: regular thorough maintenance – don’t be lazy and neglect your tools.
      Oh, and a quick tip to the noobs out there: WD40 is NOT a proper lubricant for guns, use real gun oil with the proper viscosity.

      1. avatar ACP_arms says:

        If I remember right, the reason to not use WD-40 is as it drys it leaves a gummy residue. Right?

        1. avatar joetast says:

          WD is not an oil.its a penetrating lubricant, Fuk U Duk Dienasty, u fake bastards

        2. avatar Snatchums says:

          It does have a small amount of very light oil but yes, it is NOT a lubricant. WD-40 stands for Water Displacement, formula #40.

        3. avatar Justsomeguy says:

          From the WD40 website:

          What does WD-40® Multi-Use Product do?
          WD-40® Multi-Use Product fulfills five basic functions:

          LUBRICATES: The product’s lubricating ingredients are widely dispersed and tenaciously held to all moving parts.
          PENETRATES: WD-40® Multi-Use Product loosens rust-to-metal bonds and frees stuck, frozen or rusted metal parts.
          PROTECTS: The product protects metal surfaces with corrosion-resistant ingredients to shield against moisture and other corrosive elements.
          REMOVES: WD-40® Multi-Use Product gets under dirt, grime and grease. Use it to remove gunk from tools, equipment and vehicles. WD-40® Multi-Use Product in liquid form (e.g., gallon) also dissolves adhesives, allowing easy removal of excess bonding material.
          DISPLACES MOISTURE: Because it displaces moisture, WD-40® Multi-Use Product quickly dries out electrical systems to eliminate moisture-induced short circuits.

          FWIW, in 40 years of professional mechanical experience, I’ve never found anything to be gummed up by WD40. In fact it dissolves most gummy substances about as effectively as Goo Gone or similar products. I’ve often wondered if the gum people thought was caused by WD40 wasn’t some other substance it has dissolved, but had not been wiped away. It wouldn’t be my first choice for use on my shotgun, but I would not hesitate to use it if it was the only thing available.

          http://www.brunswicklocksmith.com/locksmith/wd-40-facts-and-myths/

          https://wd40.com/cool-stuff/myths-legends-fun-facts

    4. avatar Geoff PR says:

      “So use of an anti sieze lubricant is now not recommend to prevent the “seizing” of a choke tube?”

      And on a steel barrel, copper or aluminum anti-seize?

      1. avatar Dyspeptic Gunsmith says:

        I use/recommend a thin coat of copper anti-seize, or moly disulphide grease.

    5. avatar Curtis in IL says:

      When it comes to lubricating chokes to prevent seizing, grease is better than oil, and anti-seize lubricant (Never-seez) is better than grease.

    6. avatar Don from CT says:

      No. Likely, you know more about this than the author. Anti-seize is an excellent precaution. I’ve been using it for 35 years and never had a problem.

      Don

  3. avatar Logan says:

    Thats why when I use my shotgun heavily in the fall it gets a full disassembly every weekend at least, more when it gets dirty and wet (which is everyday when duck hunting). The bolt group and choke are what I pay the most attention to for wiping down and oiling up.

  4. avatar RCC says:

    Have been using a tube of G96 shotgun grease for years. Wipe off old and put on new every time I use any of my shotguns. Not sure if they sell that version any more.

    Have meet people who have not lubed gun since the day they bought it. Have done a lot of range “gunsmithing” for these.

  5. avatar tsbhoa.p.jr says:

    old t- shirt.

  6. avatar ACP_arms says:

    Why are the choke wrench notches down in the treads on that choke?!?!

    1. avatar Mark Horning says:

      Normal for a flush fit choke (Remchoke or similar) . My Huglu chokes are the same. Winchoke/Accuchoke has the threads on the other end.

      1. avatar ACP_arms says:

        I just checked my 870 and the treads are on the chamber end.
        My question isn’t about what end the treads are on it’s why the choke wrench notches are cut in to the treads.

        What shotgun uses that choke?

  7. avatar Jericho 941 says:

    If you gonna get a frozen choke just make sure it is a modified choke. Makes sense to me.

  8. avatar 10x25mm says:

    The choke tube expansion seizure after firing steel shot is an example of autofrettage, a process used to strengthen cannon tubes and petroleum piping.

  9. avatar Jeff says:

    Why not just use choke tube lube which is supposedly designed and recommended specifically for that purpose?

    https://www.birchwoodcasey.com/Cleaning-and-Maintenance/Cleaning-Maintenance/Choke-Tube-Lube-Grease.aspx

    1. avatar Dyspeptic Gunsmith says:

      Because for the price of one tube of that Birchwood Casey stuff, you could have a 5 or 8oz jar of Permatex or other anti-seize that you can use a wide variety of uses around the house and shop.

      I’ve used copper anti-seize on muffler bolts, exhaust headers, you name it. It saves tons of work down the road around the homestead.

  10. avatar Hacksaw Jim says:

    Hacksaw. Problem Solved.

  11. avatar LJM says:

    Just an FYI to the armed intelligentsia here, there is no better choke manufacturer than George Trulock. I’ve used his products for years with great success, and anyone looking for the highest quality choke manufactured, at extremely affordable prices (especially for the quality made), you won’t be disappointed with George’s work. And being 100% American made, their pride of workmanship shows.

  12. avatar Dyspeptic Gunsmith says:

    Rarely have I had to heat the end of a shotgun barrel with a propane torch to get a mangled/frozen choke out, but I’ve done it. I heat the barrel, then spray the choke with some computer duster to contract the choke, then I try to get it out ASAP, or at least get some Kroil down between the choke and the barrel.

    FWIW, there is a tool that I’ve used to remove a choke ruined by steel shot, with Kroil, with the thermal expansion: It’s an expanding knurled internal plug:

    https://www.brownells.com/gunsmith-tools-supplies/shotgun-tools/choke-tube-tools/stuck-choke-removal-tool-prod922.aspx

    I made my own version out of a couple pieces of 1018 steel, then I case hardened the knurl with some Kasenit. You can’t get Kasenit any more, but you can get “Cherry Red” or similar compounds.

    This tool will likely ruin the choke, so it is to be used only in extremis.

    Remove your chokes at the end of every hunting season, lube the choke and put it back in. Use grease.

  13. Gentlemen,
    Over the last 35 or so years I have used oil, several different kinds of grease and anti-seize compound.
    I discussed the anti-seize many years ago with an oil company tech rep and they suggested one that was copper based.
    If you use oil it will require cleaning and replacement on a more frequent basis. However all of them do work. it is just my preference to use oil.
    I saw the comments and thought I would try to clarify.
    George Trulock
    Trulock Chokes
    http://www.trulockchokes.com

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