I tried 2-piece FLGR's and had them unscrew. Troubling, to say the least.
I went with 1-piece FLGR's and have not had any difficulty with disassembly, even in the Commander length.
The trick, for me anyway, is to tip in the guide rod from the rear, then slide the spring on. This provides just enough clearance. Trying to tip in the guide rod with spring already installed just doesn't fit.
I use a magazine held sideways as a "tool" to press in the hollow recoil spring plug, which then permits turning the barrel bushing. I understand a bushing wrench will do this as well, but my bushings aren't tight enough to require a wrench. (And then I don't have to carry a tool...)