I think that's a practice bomb, torpedos I've seen are much longer.
Correct - a 100lb practice bomb, pretty common and very cool looking. Torpedoes are huge.
https://www.nationalmuseum.af.mil/Upcoming/Photos/igphoto/2000490953/The one on ebay seems very expensive but they sold 53 of them so maybe not. i think I paid $100 for mine but I bought it long ago.
https://www.ebay.com/itm/MK15-MOD-4-NAVY-PRACTICE-BOMB-100-LB-INERT-ORIGINAL/274251029370?hash=item3fdaa29b7a:g:CTsAAOSwgPVcgXI9