Echo others, my SP01 has no real play (yet smooth as can be) with both original slide, and with another upper I got here off the forum. CZ competitor at the gun club I go to looked at it and remarked at how close the fit was even with the non-original slide. My pre-B on the other hand, rattled like mad, not sure if it had much effect on how it shot but agree it could be annoying--I think that is typical for pre-B's (family member has 'borrowed' that one indefinitely).