In our Prohibited by Amazon series, we’ve looked at items like handguards, gun slings and more. Up next we turn our attention to prohibited stocks on Amazon, namely adjustable stocks. Amazon describes these items as “any non-fixed stock, including telescoping, folding and collapsible stocks.” Adjustable stocks provide a wealth of advantages that fixed stocks simply do not. Among these is the ability to adjust the shooter’s length of pull, reduce weight, add storage space, and shorten the rifle length for close quarter use. In addition, many adjustable stocks offer sling mounting opportunities that many fixed stocks do not provide. Adjustable stocks are most popular on the AR-15 platform, but they can also be of great use on other rifles and many shotguns as well. Let’s take a look at what you need to know and then examine some popular models available at 1800GunsAndAmmo.

Mil-Spec vs. Commercial

Generally speaking there are two types of stock variants you’ll need to pay attention to when ordering an adjustable stock. These are determined by the type of buffer tube that fits into the adjustable stock. Note that one variety is not compatible with the other, which means if you buy a Mil-Spec stock and try to mount it to a commercial buffer tube it won’t work.

Mil-Spec Tubes

Mil-Spec tubes are the size determined for use by the US military. These tubes have a 1.148″ diameter and have distinct threading on the tube. The threads on the end of the tube are actually slightly larger than the tube. This variant is usually more expensive.

Commercial Tubes

The alternative to the Mil-Spec tube is the Commercial buffer tube. This tube has a diameter of 1.168″ and the threads on the tube are roughly the same size as the rest of the buffer tube.

Mounting Considerations

If you’re confused by the two variants outlined above, the best thing to do is buy the stock and work backwards. The stock manufacturer will outline the proper hardware you need to mount it, and all you have to do is buy those parts and you’re good to go. Once again, compatibility is an issue here, and you should only buy stocks, buffer tubes and parts that are approved for use with one another.

Legal Implications

Certain folding stocks are not legal in all 50 states. We encourage you to check your state regulations before ordering or mounting or purchasing a folding stock. One law that is easy to understand is NFA (National Firearms Act) short-barreled rifle laws. Attaching a stock to any rifle with a barrel shorter than 16 inches classifies it as short-barreled rifle. If the overall length of the rifle is less than 26 inches (and is shoulder fired), the classification also applies. To own a short-barreled rifle, the firearm must be registered and fees payed under the laws of the National Firearms Act.

Popular Models

Magpul MOE Buttstocks AR-15 / M-16

The standard Magpul buttstock comes in a variety of colors and is available in both Mil-Spec and Commercial varieties. This product features a shielded release latch, a removable 0.30″ rubber butt pad, and a slopping cheek weld. Additional cheek risers can be added to the stock when not used in AR-15 applications. Finally, the MOE stock accepts Magpul ASAP and ASAP-QD sling attachments, and it can fit a variety of other sling attachments as well.

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Price: From $28.78 right now at 1800GunsAndAmmo.com.

Magpul CTR Buttstocks AR-15 / M-16

An upgrade from the standard Magpul MOE stock comes in the Magpul CTR Buttstock line. Available in both Mil-Spec and Commercial configurations, the CTR line offers an important upgrade in the friction lock feature. This locking system is designed to reduce stock wobble, something that isn’t that noticeable for MOE stock users, but still makes all the difference to demanding users. Everything else on this stock mirrors the MOE line of buttstocks.

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Price: From $56.16 right now at 1800GunsAndAmmo.com.

Magpul UBR Buttstocks AR-15 / M-16

If you’re looking for even more flexibility in your buttstock, the Magpul UBR series is exactly what you need. This stock system provides the stability of a fixed stock, but the length of pull can be adjusted to 7 different positions to suit the users’ preferences. The UBR system also offers an internal storage compartment, something not available on certain other Magpul stock models. This stock comes included with the Entry-Length Receiver Extension tube you need for mounting.

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Price: $201.66 right now at 1800GunsAndAmmo.com.

Magpul PRS Precision Buttstock AR-15 / SR-25

Magpul also offers a precision adjustable stock for sniper rifle builds in the Magpul PRS Precision Buttstock. This stock is mounted like standard A1/A2 stocks (fixed stocks), but it provides adjustment for both comb height and length of pull. Even with this adjustment capability, the PRS functions like a durable fixed stock. This particular model is even durable enough to withstand the recoil from .50 BMG rifles.

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Price: $164.20 right now at 1800GunsAndAmmo.com.

Blackhawk Knoxx Gen 2 Remington 870 Adjustable Stock

Want to bring the advantages of an adjustable stock to your shotgun platform? Look no further than the Blackhawk Knoxx Gen 2 Adjustable Stock. The Knoxx Gen 2 features 7 positions of adjustment, and its patented dual recoil reducing systems help tame felt recoil. This stock also features an integrated pistol grip and several sling mounting points. You can also get it for the Mossberg 500.

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Price: From $74.95 right now at 1800GunsAndAmmo.com.

Prices and availability subject to change at 1800GunsAndAmmo.com.