Yes, you can feel the lugs cam into place if you've got just a teeny-tiny bit of crush against the shoulder. You want it to be very slight; if you have to "muscle it" even a skosh, the shoulder is too high up the case. If it's really correct, you'll actually hear a slight "swishing," metal-on-metal sound as the lugs slide past each other and lock into place. It should never be very hard to do it. If it is you're buggering your lugs, and that may very well lead to your suicide once you understand what you did...... you can with [the] firing pin out.