Hate to bring this thread back, but I did a search and here I am.
My first session back with a G5 G34 (was trying to shoot only an LEM HK for a few years, didn't work out for me) and I noticed the slide lock was getting pretty hot around the 100 round mark. I don't ever recall that happening on Gen 3 guns. My support thumb rests on the slide lock and its a nice index for me. Its very possible I didn't to that in that past with a Gen 3 G26/G34 but not probable. It was noticeable during both my session with a Gen 5.
Today was another hot day at 91 and again the damn slide lock was getting pretty hot and at the 150 round mark getting toasty.
Were these parts plastic in the past and now metal?