Old here so may have my facts tilted..Winchester in the early 60's cheaped out on their top of the line Model 70 rifles AND about the same time introduced shotguns with aluminum rather than steel receivers.
The chitchat was that they had damaged their famous franchise. I'm a Remington guy but close friend was Winchester all the way- he loved his pre-60's Mod 70 and had no complaints that I ever heard about his aluminum frame shotgun.
Long and short probably a lot of old timers remember that period in Winchester history and bad rap just ..well, just because.
My beater shotgun is a Maverick 12 gas pump with cut down 18" barrel, rifle sights with ramp front, loaded with Dead Coyote or #4 buck..its purpose is for uninvited guests. An earlier version was a High Standard Flite King I cut down and installed a Williams Foolproof receiver sight...deer slug gun, minute of paper plate at 100 yards..trigger like a rifle..just the way it came.
Enjoy your shotgun.