#6 stranded conductor doesn't fit into the hole in the neutral bar?

While trying to add a new circuit I noticed the white neutral conductor which is a #6 stranded was not fully inserted into the hole in the neutral bar. About half was in the hole and the other half "pulled back". Is this typical? I released the screw and pulled it out, cut it shorter a bit stripped the insulation, and I had a hard time pushing it into the hole as well. Is it supposed to fit? Are standard neutral bar holes big enough for the bigger conductors?