Tell me what causes the front frame rails and slide grooves to wear more horizontally in the well used 1911's? I notice this wear in every well used 1911 I look at. The rear frame rail to slide grooves remain pretty much the orginal fit while the front wears more.

No 1911 guru can answer me about this. I'm thinking it's the recoil spring putting the pressure horizontally on the front frame rails as the spring binds as it coils up. And probably your lube isn't working.

I'm a retired lead engineering tech for a engineering group in a r & d lab were we do product development and life testing, product reliability, why things broke in the field.

Seeing this wear in the front rail section on the 1911 throws a flag up as to what causes it? It's only in the well used 1911's?

My personal 1911's have the FLGR and are lubed with moly on the frame rails. No difference in wear since they were new. I lube every metal to metal contact moving part, recoil springs and guide rod too.