I have known many Remington 1100s in my time, and I like them as hunting guns. But, 500,000 rounds? In my experience, you would need about 100 1100s to make that number without replacing just about every part on the gun.
Rem 1100s at one time were common in trap and skeet. They were the best out there at the time and had relatively light recoil. However, they were not known to be particularly rugged. Try to find an 1100 in high end shooting games today. I think you won't find many, if any at all. They are still popular at local events around here though-- they are a cult favorite for some.
I have always liked the 1100, but modern Benelli's and Beretta's are way better guns in every respect.