a flex - plate adapter for a takedown firearm has front and rear sections . the rear section includes adjustment screws to change the gap between the front and rear sections . guide pins are included for assuring proper alignment between the front and rear sections . the adjustable gap between the front and rear sections of the flex - plate adapter provides compensation for thread wear . a magazine cutoff provides a manual cutoff for retaining ammunition in the magazine whether the rifle is assembled or disassembled . a cutoff lock prevents the accidental movement of the magazine cutoff .