Machining of the parts on the stock was very bad but it was cheap so I took it apart and ground them down so the stock woul lock and unlock.
Thank you for your valuable feedback on the Huben GK1 stock/brace adapter. We apologize for any difficulties you encountered with the machining of the parts. Please note that removing the handle before installing the folding stock is necessary for a smooth installation process. We understand that installing the rear stock in any other way can be challenging. However, we are glad to hear that you were able to make it work by grinding down the parts. Please know that this step is not necessary if you install the stock after removing the handle and sliding it up from the bottom of the picatinny rear adapter. We appreciate your input and will definitely consider it for future improvements. Please feel free to reach out to us if you have any further questions or concerns. Thank you again for choosing our product. Happy shooting!