This guy is pulling our chains... He says, "It will only shoot one bullet at a time now..."
He's referring to the home-made metal lever system which some have illegally manufactured to convert Mini 14's into Illegal Full-Auto machineguns. These illegal forms of Mini-14's (Legal ones called Ruger Model AC556). On most Mini14's with this lever system (which engages the secondary "sear", the "lever" sticks out to the side. This extrusion is accommodated for by the use of a wooden stock which is altered to fit the lever. However, he's referring to a Synthetic Butler Creek Folding Stock. These cannot easily be altered to fit the rifles full-auto lever. Thus you will only get semi-auto firing capabilities.
Good luck finding a way to alter the fiberglasse bedded synthetic stock, as by now any authorities on Illegal Mini-14s will be banging down your door momentarily. Have a nice day in court. [:D]
If you're actually referring to a LEGAL Mini-14, I have no idea what part you're talking about, because there is NO PART on a LEGAL mini-14 that fits that description.
How do I know all of this? I have a vast background of informal training regarding Ruger Mini-14's actions, and also the Ruger 10/22 (really fun to modify into a good tack-driver).
If incorrect, my sincerest apologies, but I'm fairly certain I'm right on the money with this.
-inuhbadnayburhood