Seeking opinions on this Ithaca M37 riot please

[ww2imposter]

The "US" stamping on the receiver and the sling swivels strike me as "odd". Thoughts?
Gunbroker # 575797972

[Allen]

GB link

http://www.gunbroker.com/item/575797972

Not the best pictures.

[Tom Doniphon]

Might help if the seller mentioned the serial number of the shotgun. It should have an S prefix to the number. But yes, the US mark is off kilter. And the US marked riots don't have the rotoforged marks. There were some riots that the Navy acquired, but IIRC, they are not US marked.

[scosgt]

If you have to question it don't buy it.
I can not read the serial number, it starts with either "2" or "8". Either way, not in any military range. I would personally not consider it legit.