thanks for the comments to all.
I had the opportunity to put on an "alternative" stock for testing.
Went to the range today and as expected everything I offered the Benelli it consumed and seemed to request more please. No issues. No surprises.
I was concerned this extra thickness in what appeared to be a washer would prevent this alternate stock from mounting cleanly. My concern was unfounded.
(sorry about the photo, Had a close up lens on the camera, the depth of field is rather thin, it was a challenge to get a photo that was not a total blur)