Even better news: I have overcome my trigger pull problems and I shot really well. At one point I tried the man's Glock just to see if the gun itself was a factor in how well I was doing. Nope. I've only tried his gun a few times before, but I took a single shot and put it straight through the center of the target :)
My shots always had a tendency to go down/right, but I'd recently gotten some dry fire rounds and had been practicing my trigger pull. Once I really paid attention to what I was doing, I discovered that I was pulling the gun to the right with my trigger finger and pulling the gun down with my support hand. I corrected that and kept practicing. When we went to the range tonight, I got to put my practice into practice and the result was that I kept slamming rounds though the bullseye. I even made some good headshots (and I've always sucked at headshots).
This was my worst target of the evening:
My hand was getting pretty fatigued by then and I had a few stray shots. But it's the only target that was exclusively mine (we'd been sharing targets before this). On my best target of the evening, I actually blew out a whole section of the red area.