I broke some steel ball bearing spring guide in one of my old VSRs. Looked like the Laylax/AA type but could have been something else.
I just racked the gun, and felt a weird clunk, fired the thing, and couldn't cock it.
The thing broke where the flat part threaded onto the main rod, where the rod was a smaller diameter and appeared to have been threaded. Who knows how many shots that thing had on it, but that seems a bit ridiculous imo.
Unless your spring guide is a one piece like a Lambda, I feel like a plastic one would be longer lasting as they are usually a nylon alloy, and nylon is bendy and shouldn't break. Both have their pros and cons, but I'd prefer to replace a plastic spring guide now and again over having a metal one as it won't wear your cylinder as much, and you'll shave weight off your gun.