Amazon.com: NERF Modulus Recon MKIII Blaster, Removable Stock and Barrel Extension, Dart Shield, 12-Dart Clip, 12 Elite Darts, Outdoor Games and Toys for Boys and Girls (Amazon Exclusive) : Toys & Games
Rotofury stock extension - gives it way better ergo : r/Nerf
Worker Nerf Simple Extension Stock (multiple colors) – Out of Darts
Nerf Saturn Stock Extension - Etsy
Pathfinder Extended Stock – Out of Darts
Blastermod StockShot Extension Butt Stock Dart Blaster for Nerf Modify toy