Spacers are only for shooting indoor speeds of 240-260. If your gun isnt shooting properly at normal 280-300 fps then you have another issue which spacers will not solve.
I havent used a spacer since 2010 and that was for trial and errors purposes.
Rediscover: "its good to see you didnt take any flying metal objects to your juggular." 13pbstar13: "I dont have tits bro" (true story)