Hello everyone, I am new to this forum and this is my first post. I hope I am posting in the correct area. I am new to AR15ing and am currently building one. I have a Colt AR15 .223. I recently installed a carbine stock to it and replaced the buffer tube. Everything is fine and feels good. When I pull the charging handle back with the take down pin pulled out it is very easy to rack back. When I push the take down pin in and pull the charging handle back it's very hard to pull. I don't understand what the problem is. Does anyone have any idea?