All,
I know this is an old thread but let's kick it up. I tried to read all the older threads but probably missed some. My first Mossberg was a 590 9 shot with the heat shield on it. I purchased/transferred it from a coworker that was into 3 gun and wanted to dump it and get a Saiga to replace it (lucky me). The only things I have done were putting on the Mossberg front and rear sights and have a tactical fore end (polymer) with three rails to replace the stock one still on it. It is a true fighting weapon in factory form as I got it, even better with the sights for slug placement (CYL bore).
I purchased a 590A1 barrel for it from the nice people at Havlin Sales & Service (wonderful people and a shout out to them). I just pulled that barrel out of the safe and it is parkerized and only marked 24 inch and 3 inch rounds authorized. No "Mossberg" identifiers or anything else. Hopefully the fore end that is in the house somewhere will still work with this barrel. It is, truly, heavier and the chamber area is substantial also (could be used by itself as an impact weapon with no damage to the barrel). There is no bayonet lug on this barrel but the 590 of mine has one. Go figure.
I was trained on Remington 870s in the USBP and have a Remington "Wingmaster" that I purchased new in 1979. Lots of birds went to the table from it. I DO prefer the tang safety on Mossbergs for offside transition, if need be, versus the Remington safety location.
I will try to post some pictures (still cannot find the camera somewhere in the house also).
JX