I've only run about 100 rounds of estate through mine at a time. Never heard of monarch, and never used American eagle.
The last time I've seen a gun get that dirty in person, was when I put a few K down the pipe in my SAW.
But, like many, I actually enjoy cleaning. It's almost a challenge, seeing just how much filth I can pull from a gun, then doing a white glove. I'm the guy that cleans a clean gun, because they bleed carbon after a while.