20ga to 357 text

357 Mag 20 Gauge Shotgun Adapters

(36 customer reviews)

$19.95$99.95

357 Magnum Shotgun Adapters for 20 Gauge Shotguns

Adapters come in 4 Lengths

2 3/4″ 5″, 11″ and 18″

All Adapters are Fully Rifled with a 1-12 or 1-18″ Twist.

Select Length below: 
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Description

357 Mag Shotgun Adapters for 20 Gauge Shotguns

357 Mag Shotgun Adapters Allow a 20 Gauge Break Action Shotgun to use 357 Magnum or 38 Special Ammo.

For 3″ as well as 2.75″ Chambers

Compatible with Break Action single as well as double barrel shotgun.

Comes with multiple O-ring configurations.  As a result,  easily achieving a good fit for 20 gauge shotguns.

Rifle dimensions are .355″/.349″ with 6 lands and .125″ wide.

Black Oxide coating as a result provides notably better corrosion protection (for maximum corrosion protection keep a thin coat of oil on the insert)

Please Note:  Not all shotguns are the same!  While the majority of them are capable of handling high pressure rounds, some are NOT.  Only use these rounds in shotguns that are compatible.  I recommend on any shotgun to test the first shot in a vice while out of harms way and to always wear eye and ear protection.  If after testing you see the primer punctured in the round discontinue using this round and use a less powerful round. These high pressure rounds include: 45-70 gov., 357 Mag Shotgun Adapters, 327 Federal, 44 Mag, and 22 Hornet.  Please always be safe and aware.
Thank you for reading.

What are Shotgun Adapters?

Shotgun Adapters frequently called Chamber Reducers or Shotgun Barrel Inserts. Our shotgun adapters allow you to use other types of ammunition in a Break Action Shotgun. Including double barrel and over and under double barrels in addition to the popular single barrel break action. We offer several different versions to suit your preference in ammunition, as well as length. 12 and 20 Gauge shotgun adapters are our most popular adapters followed closely by the 410. 16 Gauge is something we plan on expanding in the future.

Warning!

However, not all shotguns are capable of handling all of the shotgun adapters we offer. Low-pressure rounds work in any shotgun, whereas high-pressure rounds can cause problems in some shotguns. The problem is when the firing pin punctures the primer. This event causes the gases to escape and possibly damage the firing pin. All adapters chambered for high-pressure rounds have red text on the website, signifying that is is a high-pressure round. These adapters also include a pamphlet with more information about this concept. In addition These Shotgun Adapters also have a Low-Preasure round alternative.

 

357 Mag Shotgun Adapters

Most of our shotgun adapters come in different lengths to suit your needs. Some like the secure storage and portably of Shell length adapters. Whereas some are looking to get the most fps (feet per second) or accuracy out of their adapter. Black Oxide has become our standard finish. We can offer unfinished adapters during our production if you have requested one.

FPS (Feet Per Second)

As a general rule, the longer the adapter, the more FPS it produces. However, with low-pressure rounds such as the 45 colt, the fps difference is minimal once past the 11″ length. If you are interested, here is an excellent website that gives a good idea of fps per inch BBTI. All of our shotgun adapters are entirely made in the United States and are an affordable addition to your break action shotgun. Thank you for you interest in our Shotgun Adapters or Chamber Reducers. We are working to make more adapters for more calibers, so you can sign up to be notified here
The video below gives a brief demonstration of how they work.

We are working to make more adapters for more calibers, so you can sign up to be notified here. Thank you for your interest.

If you like this product, check out our other Shotgun Adapters
 

Additional information

Weight N/A
Dimensions N/A
Length

2 3/4", 6", 11, 18"

36 reviews for 357 Mag 20 Gauge Shotgun Adapters

  1. Wendy T. (verified owner)

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    Received the wrong adapter at first, but they sent me out the right on as soon as I told them. I would definitely recommend this company.

  2. sumatracarbine25 (verified owner)

    Love the 11 inch 357 barrel accurate easy to install and remove if need be

  3. Greg H. (verified owner)

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    awsome product and super accurate..will buy more as money allows..thank you

  4. Mark Renfrow (verified owner)

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    Was going to attach picture of target to review, wouldn’t post. 2 1/2″ group @ 30 yds. I’m happy.

  5. Stephen P. (verified owner)

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    Another well made product. Would buy again!

  6. James (verified owner)

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    This is a happy update. I installed larger o-rings in the three grooves on the muzzle and installed better sights. I also discovered that my barrel does not particularly like cast lead bullets.

    Using copper plated 125 gr JHP bullets I was able to get a 1″ group at 20 yards and a 3″ group at 50 yards. These meet my expectations.

    The liner is semi permanently installed in the left barrel because the oversize o-rings are very tight. I carefully reduced the portion of the rim so the ejector does not try to eject the insert.

    Now the only issue is to remember that the barrels are not regulated and to make appropriate “Kentucky windage” adjustments when shooting. This SxS shotgun/rifle is a formidable weapon.

    Thanks for the fine product.

    Jim

    So far I have been unable to get an acceptable small grouping. I installed a Marbles bullseye rear sight and a post front sight on my Stevens 20ga. SXS shotgun. The 20 yard target was a 4″ group and the 50 yard was all over the target.

    I put a beeswax thread shim under the two forward most o-rings to get a tighter fit to see if that will tighten the group.

    I intend to leave the insert in the shotgun as a “permanent” rifled barrel to augment the other shotgun barrel.

    • Chaszel (store manager)

      Good Afternoon, I am sorry to hear that the adapter is not grouping well. With the 18″ adapters try to keep the muzzle as tight as possible as you are doing. Will the 3rd o-ring install or does that make it too tight? Also after each shot make sure the adapter is indexed to the same location every time. If you planning on leaving the adapter in permanent I would recommend filling away just enough of the rim on the adapter so that the extractor in the shotgun does not move the adapter when opened. If you are not happy with the adapter you can return it for a full refund. Thank you.

      Chad

  7. Chris Kostelansky (verified owner)

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    Looks great, works perfectly. Thanks

  8. Kevin K. (verified owner)

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    Works good at 25 yards 50 yards shoots high hornady amo seems to work best used open sight just a brass dot on end of barrel . May take to gun smith and have riffel sights put on .

  9. Anonymous (verified owner)

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    Haven’t had a chance to shoot it yet but looks of good quality and with a few of my own O-rings managed a nice tight fit.

  10. Thomas Prather (verified owner)

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    Love the insert and customer service was great.

  11. Carl (verified owner)

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    great for my truck gun!!

  12. Kevin (verified owner)

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    I’m highly pleased with the barrel insert I received. The workmanship is top-quality. Your service was excellent. I’ve fired this insert in my H&R single, and the accuracy is even better than I had hoped. You get five stars for this one! I do recommend your company to others.

  13. Mark (verified owner)

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    I’m hesitate to give you this rating and not a lower one. At this point in time I have not received my order. I don’t know if the blame is on you or the Post Office, UPS, FEDEX, or some other service. I will say this, the order process went OK.

    • Chaszel (store manager)

      Good Afternoon, We really appreciate your business and understand the frustration of having a shipment take so long to arrive. Your package was shipped Priority Mail the day after you ordered it. The Post Office has been very behind on a lot of there delivery’s due to Covid-19. Your tracking say it is arriving late but is still on its way and was updated yesterday. We realize the inconvenience of these delays and have now offered UPS as a shipping option. Sorry again for the inconvenience.

      Chad

  14. Mitch W. (verified owner)

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    have not used it yet is a Christmas gift but looks good and feels well made

  15. Anonymous (verified owner)

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  16. Patrick M. (verified owner)

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    It looks great fit both single shot and double barrel shotgun good haven’t had chance to shoot it yet.

  17. Weldon P. (verified owner)

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    Beautifully made adapter. Good price and functions as it should. I will by from Chaszel again. Happy with my purchase. Thanks

  18. James Allegre (verified owner)

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    Excellent craftsmanship fitment is perfect! Unfortunately I haven’t been able to use the product yet but I expect you shortly. Dealing with Chad was a pleasure.

  19. Riley B. (verified owner)

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    Cannot wait time deer hunt with this!!!!! (I already have another insert for my O/U, this completed the gun)

  20. Kevin H. (verified owner)

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    I wanted to try the inserts out before reviewing . The purchase and delivery was simple and quick . Items were well made , well packaged and worked just as advertised .

  21. William Trader (verified owner)

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    very accurate out to 100 yrds.

  22. Paul R. (verified owner)

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    Outstanding company and products I thus far have a 20ga-.357 12ga-9mm 20-9mm and just picked up 12ga-45-70 all are great quality and shoot as they should. Can’t beat them for multitude of scenarios.This .357 model gives boosted carbine performance from my handgun sidearm loads in my survival NEF 20GA with minimal extra weight .

  23. John D. (verified owner)

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    Fast shipping,nice fit and finish.Will buy again.

  24. Riley B. (verified owner)

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    The insert is accurate and was delivered quickly. I can’t wait for more calibers!

  25. Riley (verified owner)

    I purchased a 357 Mag 20 gauge adapter and this product really exceeded my expectations. I wanted an 18 inch adapter, but that wasn’t available. The 11 inch adapter was and it is excellent. I set up a target at 55-60 yards (the area around the 50 yard mark was muddier than normal), I put four shots within a 6 inch circle on the paper. I need to practice more and I’m sure accuracy will go up. I moved the target to 100 yards. At 100 yards, it should be known I have a Stoeger Conder 20 ga O/U. So in terms of bead placement, the bead covered the entire target. My first shot was a flyer as it was high and right. The last three shots were more or less just outside a 6 inch target. It was all to the right, but I was using a bead, not rifled sights. The 11 inch insert went 8/8 for shots on paper, it is consistent and easy to use. I know changing sights will make an impact and I will explore some of those. I can’t wait for more caliber to come out! I plan on using this for deer season this fall, I just need to practice more first.

  26. steve (verified owner)

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    excellent workmanship

  27. Dean Santomango (verified owner)

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    Excellent quality

  28. Anonymous (verified owner)

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  29. John (verified owner)

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  30. Anonymous (verified owner)

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    Quick delivery and on checking up the adapter, the machining looks excellent.
    I did put a note in the Graybeard forum about the product.

    • Chaszel (store manager)

      Thank you for your product Review, We really appreciate it.

      Chad

  31. James Ballou (verified owner)

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    Chaszel makes a super high-quality, well designed and finely machined product, they mail the orders right away, their prices for these types of products simply cannot be beat, and in my experience their customer service is outstanding.

  32. Amanda McGowan (verified owner)

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    I could not be more pleased with this product. It has breathed new life into my topper jr. I plan on purchasing more calibers when they are available.

  33. Mark Wilson (verified owner)

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    quick reply, i like the interaction, overall great experience, would recommend again

  34. Jeremiah wimmer (verified owner)

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    Awesome product works amazing it is as they said

  35. Troy D. (verified owner)

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    I have not used the 357 insert yet, the bore for the bullet casing seems a little large. mic’d at .3805. Measurements on the 357 cartridges I have are .3755 so have a little play when placed in the insert. Bore is correct and the lands and grooves look great..

    • Chaszel (store manager)

      The loose fit is normal. Saami specifications call for .381″ at the opening. If you have any other concerns or questions feel free to let me know. Thank you very much for your business and your feedback.

      Chad

  36. Corey W. (verified owner)

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    Sent me the wrong one. When I emailed them they immediately returned my email and sent me the correct one. Great product and great customer service.

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