Sylvan Arms AR-15/AR-9 Folding Stock Adapter Gen 3 – ARH300

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An Innovative Tool To Transform Your AR-15/AR-9 Into A Folding Rifle

The Sylvan Arms AR-15/AR-9 Folding Stock Adapter Gen 3 – ARH300 is an innovative accessory that will allow shooters to easily adapt a Mil-spec AR-15 or AR-9 pattern rifle to a folding stock configuration. This will help significantly in reducing the length of the rifle for easy stow and travel.

The ARH300 is specifically designed for gas piston and direct impingement systems 5.56 to .308 systems, as well as .223 compatible, it has standard 1-3/16” x 16 thread and does not require any additional parts to be used with standard BC Groups. Can NOT be fired when open.

Easy Installation – No Special Tools Required

The Sylvan Arms AR-15/AR-9 Folding Stock Adapter Gen 3 is CNC machined from 7075 Billet Aluminum making it uniquely lightweight and corrosion-resistant. Adding this accessory to your AR build requires no specials tool except for a standard armorer’s wrench and the assembly weighs only 6.0 ounces.

Simply screw it into your receiver like a buffer tube, add your favorite buffer tube and stock, and you’re good to go.

Now Compatible with Silent Capture Buffer Springs!


  • Allows folding stock for compact storage and carry.
  • Weighs just 6.0 oz.
  • Precision machined from B390 aluminum.
  • Durable H-series Cerakote finish.
  • Does not require special tools or parts.
  • Designed for mil-spec 5.56 and .308 caliber AR-pattern rifles.
  • Compatible with direct impingement and gas piston rifles.
  • Adds just 1.3 inches to rifle’s length in firing position.


  • Comes with a standard .625 bolt extension.
  • Fit: platforms .223/5.56 to .308 & most 9mm
  • 9mm bolt carriers with 5/8 ID (.625) standard sizing can use the bolt extension included, after removing the pin and weight from the bolt carrier
  • If your bolt carrier group is causing the bolt extension to come up short contact us for a conversion
  • 17/32 .531 bolt extension for smaller bolt carriers
  • Compatible with Silent Capture Buffer Springs if you use our Silent Capture Bolt Extension
  • 300 blk (blackout) compatible
  • Adds 2 inches to length of pull
  • Surface treatment: hard coat black anodized
  • Material: 7075 CNC-machined billet Aluminum
  • Thread specifications: 1-3/16″ X 16
  • Hinge dimensions: 3 11/16 inches
  • Hinge weight: 6.0 oz, BC – Extension 3.1 oz
  • Hinge length: 1.3 inches
  • Warranty: Limited lifetime

Have Questions About this Product?

The AT3 Tactical store has a 90 day no-hassle return policy for products in good condition. You can view the full details of our return policy here.

If you encounter an issue or defect with a product after 90 days of your purchase, you can refer to the manufacturer for a warranty claim. Their policies are below.

Sylvan Arms Warranty

We stand by our products!

If you are experiencing an issue with a Sylvan Arms product, please contact us at your earliest convenience so we can address the issue. Our goal is to make it work for you so please give us all details possible. Not every product is 100% compatible, with variations in build, but we will do our best to make it work with your components.

We have a 30-day hassle-free return policy. If you would like to make a return please request an RMA number from our customer service department. We reserve the right to deny return requests if the item has been intentionally damaged beyond repair.

Contact Details:

  • Telephone: 888-256-5632
  • Email:

Disclaimer: Manufacturer’s warranty is subject to change without prior notice.

Customer Reviews

Based on 11 reviews
Russell Pence
Great on my AR-9

Got this not to long ago, but I will say it was pretty simple installing it and sure does feel good and looks even better. Already put around 350 rounds threw my gun with zero issues. Would definitely buy again! 5/5.

Thanks for sharing your feedback! We're glad you're satisfied with your purchase.

Michael Peterson
My second one

This is my second Sylvan folding stock adapter. I got the first one about a year ago and put it on a lower shared by a 5.56 and a .300 BO. I like it so much, I wanted one on my 9mm AR. I installed it on the lower and removed the weight from the bolt carrier to fit the extension. I haven’t fired the 9mm since I installed it but, the function check went fine. Now, I have two folding stock lowers for the price of one of the other guys. You can’t beat that.

Thanks for sharing your feedback! We're glad you're satisfied with your purchase.

Brian Boros

No Logo on unit so enough said

Nick Proscia

Fits like a glove, great quality...will be ordering another one for my next AR pistol build!!!

Thanks for sharing your feedback! We're glad you're satisfied with your purchase.

Bryan Sprague
Great service

They worked with me to get the perfect parts for my project. Thanks

Thanks for sharing your feedback! We're glad you're satisfied with your purchase.