the most current AR15 that I built would not take the entire spring and detent for the front take down pin. I could not push the spring and detent down enough to get the pin started in the hole. The spring would compress all the way and bottom out and I am 100% positive I had the right detent and spring. I ended cutting off about 1/8" of the spring off and it worked perfectly fine.
Is it just the spring and detent hole not drilled to spec for depth?
It all works perfectly fine now, was just curious what you guys though.