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Gold 20-28The 20-28 GaugeMate Gold adapter started out with an axially split design, much like the very successful 10-12 and 16-20 gold adapters. As you may or may not know, these are the thin wall adapters that do not have room for an o-ring to provide the friction for retention in the chamber upon extraction or ejection. However, the larger wall thickness in the 20-28 is such that the hull of the 28ga shotshell becomes split where it is not supported along the length of the slit. Because many people shooting 28ga shells like to reload, we took our customers’ input in redesigning the adapter. The slit has been removed with this new design, providing more support. For those users that wish frictional retention of the adapter in the chamber, we have found that a spreading a thick layer of lube on the outside of the adapter provides just enough resistance to keep the adapter in the chamber of the gun. If you have a looser fit, you may find that a thicker lubricant, such as marine grease, is more effective for you. Please Contact Us with your input as we are constantly striving to improve our products.

Extractor-Grip (specially for 410 conversions)

Extractor Grip

The Extractor-Grip is a patent-pending design feature on our Silver adapters that use .410 ammo. A pair of spherical cutouts allows the spent shell to be directly grasped for removal by the thumb and forefinger. This greatly eases the changing of shells. Other adapters on the market require you to have tiny fingers or use a stick to remove the spent shells. With the Extractor-Grip, you simply pull the spent shell out with ease.

The Slot

The Slot

A patent-pending design feature on our 10-12,10-12XL, and 16-20 adapters. On adapters with a thin wall section, the material is not sufficiently thick to maintain its form. Our solution is simple, yet effective. A lengthwise slot allows the chamber to directly support the adapter during firing.

*Cases fired in split adapters will probably not be reloadable.

The Tapered End

Tapered End

Not all guns are equal. Some European designs have shorter chambers that require you to use hard-to-find 2-1/2” Ammo. The taper allows the adapter to reach past the forcing cone in these guns. All Gauge-Mate adapters (except 10-12XL) are designed to fire standard-length ammo from any break-action shotgun with all chamber sizes.


Exclusive Features to the "Stays in the Gun" Gold Series:

The Cutaway Rim

Cutaway Rim

With GaugeMate-Gold, the cutawasy rim allows you to remove the spent shell without touching the adapter at all! The remaining rim portion aligns with the ejector/extractor so the adapter will move as it does. With the rim cut away, the end of the shell is presented for easy removal. Once the adapter is in place, subsequent reloading takes virtually the same time as using the normal ammo for the gun.

Friction Retention


To achieve proper operation in every model, there is a need to provide the necessary friction to retain the adapter in the gun, yet allow the ejector/extractor to present the shell for removal.
   Stvle A: 10-20.12-20.12-28. and 16-28

Three grooves of different depths may be used with standard or oversized o-rings to provide the correct amount of friction.
   Style B: 12-410.16-410.20-410, and 28-410

A single standard or oversized o-ring provide the right fit for the gun chamber.
   Style C: 10-12.10-12XL.12-16.20-28. and 16-20

Slotted feature provides the required friction in the chamber through spring tension.


The Designs

Cutaway Rim

Designed by Henry Fletcher, GaugeMate adapters are an elegant solution for adding utility and value to the gun you already own. Working exclusively with stainless steel, Mr. Fletcher has developed an adapter family that will allow your shotgun to fire virtually any smaller standard shotgun gauge ammunition. The exterior of our adapters mimic the outer dimensions of high-quality ammunition, giving a precise fit with your gun. The interior is dimensioned and toleranced like the chamber of a fine firearm, holding the smaller shell securely in place.

Shotgun ammunition varies greatly in both style of construction and quality. Some "promotional ammunition", while available at very low prices, does not work well in any adapters. We have found that Winchester AA and Remington STS ammunition performs best in Gauge-Mate adapters.

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Adapter Info

See GaugeMate's sub-gauge adapters in action in our Gaugemate Challenge Video
gaugemate video

Learn more: "How Sub-Gauge Adapters Work

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