I purchased a used Gen4 G19 w/ ATEI installed RMR a few months ago, and have plans to give the set-up a dedicated try this coming shooting season. Last time I took it out I noticed a few scratches on the RMR housing and wondered if it was the brass deflecting off the RMR. Prior owner confirms scuffs are pre-existing. I installed the Apex FRE anyway, but this leads me to ponder a few questions:

1-Can BTF damage the RMR glass? Mostly just curious.

2-How tough is RMR glass? I hear some people rack their slides with it.

3-Can brass even hit the RMR? Does the ejection angle even allow it?

I'm guessing the best solution for people setting up the Glock/RMR combo is to vet your pistol before having RMR installed.