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The search results show that amateur lunar laser ranging is not feasible — you'd need a massive laser (10^17 photons/pulse) and observatory-grade equipment to detect the ~2 photons returning from retroreflectors. Here's the main discussion: Reddit r/askscience thread from an APOLLO project grad student and Physics Stack Exchange on the technical barriers. No documented amateur successes found.

what about just to detect that retroreflectors are on the Moon, so no distance measurements are needed. Couldn't amateur just fire the laser for a long enough time to get sufficient reflection back to confirm this?

Still no — even with extended exposure, the signal-to-noise problem remains insurmountable. The Reddit thread explains that without short pulse widths you can't filter background photons, drowning out the ~1-2 reflected photons. Continuous beam just adds more noise, not more signal.