My upper was really tight. I don't have an optic on the handguard... yet, so I squeeze down with my palm of my hand on the upper, tilt the rifle sideways and my pin falls out.
The original pin was hard to grab the by the head, so I replaced it with a threaded machine screw, which I like way more. The new 'pin' pops out easier then the original. It doesn't screw in.
I cut the machine screw 2mm longer then the original. The thread prevents the pin from backing out. So far so good. I also cleaned up an imperfection on the pin grove on the upper that made pin removal rather difficult, now it take half the effort to remove the upper.
With the little tweaking I did, the upper is super solid and I'm pretty confident it will still hold zero with an optic mounted. I have the option of using the original pin, but I like the look and performance of the machine screw.