I just crossed 3,000 rounds on my Mossberg 500 Field that I bought used in 2015. The only maintenance has been cleaning after every session, one recoil spring replacement at around 1,500 rounds (probably didn't even need it) and a new follower because the original one got dinged up. I must say that this is the most reliable firearm I own and I own quite a few. Just thought I'd share for anyone on the fence about a used 500... buy it. They run forever!