Can Anyone Help with M&P9 Magazines?

[dullh]

... but I see a lot of 40/357 M&P mags in my area but the 9mm ones have been gone for a while...how different is the 40 mag? Does it fit? If it were loaded with 9mm ammo would it work in a full size M&P? Has anyone tried it?

Same here where I am...my local gun shop has 15rd .40 magazines in abundance, but the 9mm magazines are like Sasquatch - everybody's heard of them but nobody's seen them!

I would not modify a .40 magazine in a desperate attempt to feed your 9...doing so will compromise reliability right off the bench.

 

[Roger S&W]

UPDATE: A generous member who requested to remain anonymous helped me out. I soon will have enough magazines to shoot competition. And he didn't try to rake me over the coals with exploitive profiteering either.
Stand up guy, all around.