My .40 works just fine with my 9mm mags.
Slab sided mag tube, unmodified follower, wolff caspian spring trimmed to 10 coils, and CMPI extended aluminum basepad.
That combo gets me 20 9mm or 15 .40's per mag, and is just short of 140mm. WIih a different follower and spring, I could probubly get anther 1-2 .40's, but I haven't looked very hard for them. Maybe if I gave a mag to Bevin and told him price was no concern
