I only have experience with two semi-autos. 1100/11-87's and Auto 5's (the original Auto 5).
My Auto 5 looked really bad when I bought it. Sort of a rusty brown color. Checkering on the stock/forend worn almost smooth, very little finish left on the wood. Got a good deal on a "poor" rated old shot gun.
Got it home. 0000 steel wool and oil and elbow grease revealed only one small area of pitting on the receiver and a lot of the finish was blue after the light rusting was removed.
Inside it was filthy, bad, really nasty.
The magazine spring was broken in two. Someone had used pliers to twist the two broken ends together and the darn thing still worked. The action spring guide was the original old piece of factory wood. Yeah, a wooden spring guide, back there in the stock/receiver. So dirty/black I thought it was some type of plastic/phenolic till I got the crud off it and saw the grain. Seemed good once cleaned so I re-used it. Put all new springs in it and added a magazine tube extension. Sitting behind the bedroom door right now with 9 rounds of 00 buckshot in it. Just as smooth as the day it was made back in 1934. No doubt it's uglier, but it still runs like a champ.
John Browning knew what he was doing.