The Utility of 12-Gauge Caliber Adapters, The Good, Bad, & Ugly

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WoodTrekker has put up a comprehensive overview of their experiences with 12-Gauge caliber adapters. To sum it up in a few words, down-gauge adpaters (.410 and 20-gauge) work well, .22LR is short-range practical, but everything else is a resounding “meh.” This is result of the combination of loose fit of the adapters, short barrel lengths, and the cost/weight for each individual caliber.

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Their summary of the rifled adapter results lays their thoughts out clearly:

Does it work? Not really. Yes, the adapters will let you shoot the desired ammunition. In that sense they do work. However, this is a prime example of how just because you can shoot something out of a gun, it doesn’t mean you should. The reason why I say that they do not work is because of the atrocious accuracy. I suppose accuracy is a relative thing, and for a pipe gun (which is what this combined with the shotgun actually is) it is fairly accurate, but by rifle standards, it is horribly inaccurate.

This should be no surprise for any rifle shooter. Using such an adapter is the equivalent of shooting a pistol with a loose barrel. All of the things that we spend so much time on in order to achieve accuracy: bedding the action, free floating the barrel, measuring tolerances, are not only not done here, but rather what we have is quite the opposite. We have an insert which gives us a firing platform separate from the action, it’s position changes with each shot and even every movement of the gun, and the insert is not bedded properly, touching the barrel and moving around under the pressure of the detonation. Most people blame the inaccuracy on the short barrel (either 3 or 8 inches depending on the model), but that is not the main problem. Many handguns like the Ruger Mark II and the Browning Buckmark will shoot close to 1 inch groupings at 50 yards all day long. The mechanism of the shotgun rifled chamber adapters however, prevents such accuracy regardless of the length of the insert.

The lack of accuracy is not a product of poor quality either. The adapters are very well made and are good quality with attention paid to the details. Unfortunately, the technology itself can only be pushed so far.

However, adapters that allow the use of smaller gauges and black-powder work very well. Trekker contends they add versatility to your shotgun for little weight and cost but are ultimately not practical as the shot patterns degrade faster.

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Does it work? Yes. These adapters, at least in my experience, work very well. The patter you will get out of the shotgun will not be amazing (it will be similar to shooting out of a cylinder choke), but at 20 yards and maybe even more, a 20 gauge shell shot out of a 12 gauge shotgun will give you a decent pattern. When you start to go to smaller shells like the .410, the pattern will degrade much faster because of the bigger difference between the 12 gauge barrel and the .410 shell, but it will get the job done.

Is it practical? Not really. The theory behind these chamber adapters is that you get the added versatility of using whatever shells you can find. While that is true in theory, we are talking about wilderness self reliance or survival here. When is the last time you were somewhere in the wilderness, and found a box of ammunition… any ammunition? The answer is probably “never”. A Short Lane 12 Gauge to 20 Gauge Shotgun Adapter weighs 3 oz and costs $25. It will work as it is designed, but if you don’t have a realistic chance of finding 20 gauge ammunition in a wilderness survival or self reliance situation, then it is dead weight. If on the other hand your idea of wilderness involves houses, farms, and gun stores, then maybe this would be a good option. With prices of 20 gauge ammo often being higher than that for 12 gauge ammo, the benefit is not clear to see.

The only circumstance that I can think of where such an adapter could be of practical use, is if you are out hunting with your 12 gauge, and your hunting partner is using a 20 gauge, and you want to be able to bum ammo from him. Then a 3 oz adapter makes sense, and can be quiet handy.  

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What do you think? Is their experience spot-on or have you found them to be more useful?



Nathan S.

One of TFB’s resident Jarheads, Nathan now works within the firearms industry. A consecutive Marine rifle and pistol expert, he enjoys local 3-gun, NFA, gunsmithing, MSR’s, & high-speed gear. Nathan has traveled to over 30 countries working with US DoD & foreign MoDs.

Nathan can be reached at Nathan.S@TheFirearmBlog.com

The above post is my opinion and does not reflect the views of any company or organization.


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  • Raven

    12-to-20ga adapter. No way that could go horribly, horribly wrong. It’s not like mixing up 20ga and 12ga shells is the leading cause of KBs in shotguns or anything.

  • JaxD

    You sure that last pic isn’t “smoking” accessories?

  • MIKE

    Yes, it is true 12 gauge is cheaper than 20 gauge, however during the darkest days of ammo scarcity…I was able to find 20 gauge when there was nothing else at wal-mart or gunshops. So, I picked up a mint condition, 30 year old, H&R Topper 20 gauge for $60.

    • Geodkyt

      Yup — the quality of that H&R’s patterns was probably EASILY significantly more than twice that of a chamber adaptor, and was easier to deal with in the field.

      So, your second shotgun was cheaper (or at least no more expensive) than the adaptor, when viewed as “bang for your buck”. Especially since, you now have a loaner gun so TWO people can be shooting at once, if you choose.

  • wetcorps

    I always liked the idea, but marketing this stuff as “survival gear” seems a little far fetched indeed.
    Those are designed for the kind of scenario you see in Mad Max or The Road, where people fight over the last round of .44… Unlikely in our lifetime, especially in the US.

    They sound really fun for plinking though 🙂

  • Nimrod

    I am a big fan of single shot shotguns and adapters but only for the gadget factor not for any practical value. Like the article says, they work but not very well.

  • Samuel

    My son learned to fire a shotgun using 28 gauge handloads in a 20 gauge single shot with a ‘little skeeters’ adaptor. Less blast and recoil, decent patterns and I didn’t need to buy a 2nd shotgun.

  • opie7afe

    i think a better option would be to make a full length adapter with a cone shaped nut on the muzzle end that you can tighten up. this will keep everything centered, while keeping barrel tight and will give you a chance at being accurate. would not be hard to do but of course these companies would charge a pretty penny for it…the concept is not hard to do just turn the barrel OD to the same specs as the saami chamber (minus a thou or two). then of course thread the muzzle end(for the cone lock nut and have enough threads for a supressor if you wish) would be a great seller imo…i know of one shotgun that was for sale on a forum where they welded a .357mag into a 20 gauge chamber. worked pretty good from what i read.

    • Geodkyt

      Yeah, but then you’re tied to a specific barrel length AND the adaptor weight goes through the roof (relatively speaking).

      But that is how a lot of military subcaliber devices (earliest I’ve seen like that for small arms was for a .450 Martini-Henry, latest was for an HK G3).

  • MIKE

    I read the original article on woodtrekker.blogspot.com. The entire piece is qualitative. No quantitative data was data was provided. I would like to see group and velocity data at each target range. I believe comparing a chamber insert to a rifle is absurd. A better comparison would be to a .22lr pocket pistol like a Taurus 22PLY or a Beretta 21A for a 3 inch chamber adapter.

    • Ross Gilmore

      I think that’s the point Mike. You can have fun with the adapters, but if people expect that they will give you a substitute for carrying a proper .22LR rifle, they are fooling themselves. If you brought a 12 gauge shotgun into the woods as your only gun, and you brought .22LR ammo with you to save on weight, in the hopes that you can effectively hunt with it with a .22LR adapter, you are going to be very disappointed with the results.

  • MIKE

    I’m going to leave this here: https://www.youtube.com/watch?v=P5AoJYsFDxw#t=195

  • PhAxel

    Could probably be made to work well (or more consistently, at least) with a heat resistant silicone washer or two. Or even a little electrical tape as a temporary solution. Something to make it a tighter fit.

  • mike

    Just saw this. Sub-gauge adapter tubes have been the staple of competitive skeet and other shotgun sports for decades and work exceptionally well. There are a lot of people shooting 12 gauge shotguns that have never chambered or fired a 12 gauge load through those guns. Only works on break-actions, though.

  • Mike

    The rifled GaugeMate 2-3/4″ adapter I use with a Mossberg Maverick 88 pump will easily and constantly shoot minute of rabbit at 25 yards. These are chest hits, not gut shots. I can also make a tennis ball dance at the same distance.

    What I have found is that your accuracy with a rifled adapter isn’t effected nearly as much by the fit of the adapter in the chamber, but rather how well your shotgun’s sights work with the adapter, and how well the shooter uses the two together. Sometimes it all works harmoniously, sometimes, for whatever reason, it doesn’t.

    Anyone who has been keeping track of the YouTube videos produced by Dave Canterbury at Pathfinder will notice that he’s had better sights installed on the barrel of his H&R single shot simply to get better accuracy out of his adapters.

    Only expect any accuracy out of a rifled adapter for a cartridge that is designed to be used with rifling. Many cartridge adapters are smoothbore.

    The GaugeMate 2-3/4″ rifled adapter has the same barrel length as a short barreled handgun but a more stable platform. A 40gr lead bullet from a high velocity .22LR round will still penetrate 11 inches of ballistic gelatin.

    Indexing the adapter so the offset bore is at the same ‘clock’ position in the chamber also helps. I prefer to always have the adapter’s offset bore in the 12 O’Clock position. It takes a bit of practice to always get a proper index you drop the adapter into the pump shotgun’s chamber.

    The GaugeMate has a set screw you can tighten to hold a cartridge while the adapter is run through the magazine, but I never do that. It’s best to just use it like you are single loading a round, with the muzzle pointed down. Pump’s can easily be used like a singleshot in this manner.

    Don’t use the Short Lane Zombie 3″ .22LR adapter in a pump because in order to save a machining step in recessing the base to keep the firing pin from hitting steel when it hits the cartridge rim, they moved the .22LR bore offset about 0.018″ so the firing pin hits all brass without a recessed base. To set the primer off they took advantage of how a break action’s firing pin is normally a bit wider than a pump’s firing pin. The Short Lane .22LR adapters work in a break action but a pump has a hard time getting a round to fire with one because the firing pin strike is just a bit too far in from the rim.

    That is why with a pump action you have to use a rimfire adapter made by GaugeMate. A centerfire adapter from any maker will work in a pump.

    The sub-gauge shotshell adapters work well, and allow you to use for things like foraging and hunting extra ammo that you have laying around, that you have found in the garage, bought at a swap meet, etc. This country is awash in shotgun shells, but the overwhelming majority of it is in three gauges: 12, 20, and .410. In a crisis these allow you to forage with any shotgun ammo you obtain, while conserving your native gauge ammo for when it’s really needed.

    As for the Short Lane blackpowder adapter, that is kind of a solution looking for a need. You can reload a scavenged modern plastic shotgun shell with blackpowder. The newer plastics are better than the older plastics for this. You can also buy online for about the same price as that adapter a box of 25 all brass shotgun shells made by MagTech. They use large pistol primers, but you can drill them out to use 209 shotgun primers.