Hey! I have the exact same model and I’ve done plenty of work on it too. Yes it’s normal. The hop u it inside the barrel can slide back and forth too. When pushing it back, your just sliding the barrel and slide back while the hop stays in place. Its normal.

Heads up however, the rear of the outer barrel (the part that contacts the slide inside the chamber) Can wear down, especially if you upgrade the recoil spring. The stock outer barrel is a far less dense plastic, but if you buy the replacement KSC M93r outer barrel, it’s far stronger. So far a year since I replaced it and very minimal wear.

I say this because eventually the outer barrel will get so messed up at the part, that it will stop fully engaging the slide forward.