Insert the loaded mag into the pistol with the slide locked back, and then release the slide with the slide lock lever to chamber a round. Then, release the magazine, top off the magazine with one more round to fill it. Now insert the full magazine into the grip. The slide should already be forward on the loaded chamber and now there is a full magazine in the grip, giving 6+1 for the CM9 or PM9.
From your confusing explanation, it sounds like you're racking the slide again after the chamber is loaded and a full magazine is inserted... yeah, this can cause problems. Ejecting an unfired round requires a robust racking of the slide and is complicated by another round feeding up from the magazine. You don't want to do that. You want a round chambered... that's the +1, then insert a fully loaded magazine... without any further racking! The metal thingy back on the left inside rear of the frame is the ejector. When you don't rack the slide robustly... as when firing the gun... things can interfere as the top round of magazine and the unfired round being pulled to the rear with the extractor.
To UNLOAD the pistol, FIRST remove the magazine, then point in a safe direction with the ejection port pointed at the ground, rack the slide briskly to eject the unfired cartridge. With the port downward, gravity helps the cartridge leave the chamber... otherwise it might fall back into the frame and hang up, or out the magazine well.
Wynn
USAF Retired '88, NRA Life Member. Wife USAF Retired '96
Avatar: Wynn re-enlists his wife Desiree, circa 1988 Loring AFB, ME. 42nd BMW, Heavy (SAC) B-52G's
Frédéric Bastiat’s essay, The Law: http://mises.org/books/thelaw.pdf
Thomas Jefferson said
“A government big enough to give you everything you want, is strong enough to take everything you have.”
and
"Peace is that brief glorious moment in history when everybody stands around reloading".