Well, guys, thanks again for your concern and advice. I thought I was doing everything fine, but obviously I wasn't.
Ironically, I've had Snap-Caps for other guns, but the .45 was always out of stock. Today I found some. And they have made a world of difference. Guns are sold with nearly all the basic stuff needed nowadays, but they should include Snap-Caps too.
I took my XD to the gun store and consulted with a couple of the experts. They quickly assured me and demonstrated that the XD does NOT lock open with a loaded magazine.
So as some of you mentioned, my practicing with an unloaded magazine was almost worse than not practicing at all because I was not only making wrong assumptions but doing wrong "corrections."
To my embarrassment I realized my left hand is not strong enough to reliably chamber shells in the pistol! Geez I hate that. But, gotta face the facts. I was dinking and fudging the slide when I should have been snapping it with authority.
Fortunately I have no trouble holding the XD in my left hand and cocking the slide with my right hand. That's what I should have been doing all along. My own quirky but effective way of fixing the problem.
Without the Snap-Caps to verify if a shell was in the chamber, I had no way of knowing many of my make-believe chamberings were not happening. As Virgil in particular was warning me, I was "learning" the wrong lessons.
This has been a revelation. I'm not even going to try cocking large pistols anymore with the traditional right hand hold and left hand ****, both hands facing forward.
Instead, I need to hold the pistol in the left hand, hand facing backward, and **** the slide with the right hand facing forward and pulling backward. Sets up much better opposing forces for me. Know thyself, huh?
Mighy take a few more seconds, but better slower and correct than faster and wrong.
The XD as always is perfect. What a great gun. Still my favorite home defense and plinker. But much as I studied it, I didn't continue far enough to graduate with the Snap-Caps. Now I think we're combat ready, although as many of you have said, only with good periodic practice to include, of course, shooting at the firing range.
Thanks again to all of you for insisting I realize something not only was amiss but needed to be fixed quickly, and then showing me the best way to do it.