Mine is also the MW Supreme Reversible Rotary Model 30....& mine takes a 20x1, Boye 21 or 14, etc. I have a MW needle packet in front of me right now....& like I said their # is A85-1222....& they're 1 3/4" long.
OK...just looked at the back of the packet. There it says "Type A85-1222 are for the following sewing machines: Wards Reversible Rotary EXCEPT for aluminum & open arm models"!!! There's where the difference lies. Your's must be one of those "EXCEPTS", Glenn. I use mine quite a bit (as did Grandma!) & it won't even pick up the bobbin thread with a 15x1! I know for sure mine's not aluminum...it's kinda like lifting a locomotive to even pull it up in it's cabinet!