my open gun has port very close to the barrel end , and it chips the edge of my signed side blast shield of my rts2 , With both standard size and wide frame size mount , so I got a double tap double side mount for rts2 that sit the dot tight middle of the slide took care of the problem , but now 510c gets more popular so kinda want to try , as the deal shop here gave me 2 , just now have to decide what mount I am going to use