Hey Guys. I have a PRI front flip up sight base that uses four set screws to hold it on the .750" barrel. I'll include an excellant condition USGI 30rd mag with a new green follower to sweeten the deal. I have two different barrel projects going. I will need to open up the gas hole slowly. The PRI flip up front sight base that uses two allen cap screws would be much easier to install and remove the multiple times I might have to adjust the gas hole. So, I would like to trade the one that I have for either a .625" or .750" double cap screw model. My unit still has the box and is in very good condition. Please let me know what you have. The email button is the best way to contact me. Thanks for your time.