9mm vs 40 S&W magazines

[Gokyo]

I just noticed that my T9 magazines and T40 magazines look virtually identical expect for the roll mark.

Can anyone confirm this or speak to interoperability.

Thanks

[wyntrout]

They aren't interchangeable. I tried to "stretch" the 9mm tube, but that didn't work. There is an internal size difference, but not worth trying to get to work either way. Stick with stock for reliability... the most important thing. The only mods I could get away with involved replacing the plastic base plates with the 9mm metal ones and even then I needed use a 3/32"x 3/4" Inner Diameter neoprene O-ring to preclude pinching, especially by the .40.

[Gokyo]

They aren't interchangeable. I tried to "stretch" the 9mm tube, but that didn't work. There is an internal size difference, but not worth trying to get to work either way. Stick with stock for reliability... the most important thing. The only mods I could get away with involved replacing the plastic base plates with the 9mm metal ones and even then I needed use a 3/32"x 3/4" Inner Diameter neoprene O-ring to preclude pinching, especially by the .40.
Do you have a parts# for the metal base plate I would like to acquire some of them.

[Scott321]

I just noticed that my T9 magazines and T40 magazines look virtually identical expect for the roll mark.

Can anyone confirm this or speak to interoperability.

Thanks

I tried to fit my Lakeline magazine sleeve for my 9mm onto my 40. It wasn't wide enough. The difference is tiny, though.

[wyntrout]

Metal base and lock for 9mm/.40: https://shopkahrfirearmsgroup.com/search.php?search_query=9mm%20base%20and%20lock%20 kit&section=product