Stock Adapter UFM4-AKMS (Underfolder)


This model works with AKMS Underfolder receivers with square rear trunnions (non-angled).

  • Drop-In installation on AKMS Models and other under folder variants with square, non-angled rear trunnions.
  • Can be installed onto Pistols with intent to use Arm Braces. Gun Smith installation recommended with pistols (requires drilling the receiver for the 4 screw mounting holes.)
  • Confirmed Rifles: Polish AKMS, Russian AKMS, Hungarian AKMS, and most other AKMS series Stamped Under Folders.

In stock


The Definitive Arms UFM4 Stock adapter series is the lightest and strongest way to allow the usage of M4/AR15 style stocks, buffer tubes, and pistol brace tubes on common Under Folder AK variants with a simple to install completely drop in assembly.

  • The UFM4 series is compatible with original spec Under Folder AKs (make sure your model is listed above)
  • Completely Drop-In part, installs in minutes with zero alterations or fitting required. *
  • Machined from solid Aluminum.
  • Anodized Finish (MIL-A-8625 Mil-Spec Hard Coat Anodized)
  • Includes hardware and tool for installation (Flange nuts, alloy steel screws, allen-key tool)
  • Simple screw and flange nut attachment, with aluminum flanged wings for a breaking strength that exceeds buffer tubes themselves.
  • Aligns buffer tube closer to bore line for better recoil management via flatter recoil impulse.
  • Increased stock height for improved use with optics equipped AKs and still allows comfortable operation with open sights.
  • Accepts Mil-Spec and most after market buffer tubes, end plates, and castle nuts.
  • Weight: 2.2oz


* Note: 100% Drop in installation assumes you have an In-Spec rifle with proper rear trunnion and receiver dimensions. Some rear trunnion variations or slightly misaligned receiver to trunnion builds, may require light fitting or holes to be properly clearanced. No fitting is required on a quality in-spec properly built AK or Under folder AKs that have had a working mechanism installed in them before.
This version is for the STAMPED AKMS pattern AKs.
NOTE: We will not refund/exchange adapters that have been altered for models it was not designed for.

Additional information

Weight 2.2 oz