Sure enough,they do have the same number of coils.Just checked all of my FNP-45 magazines to confirm,3=14s and 4=15s.
As I said earlier my 14s are VERY stout.Upon checking them all of mine are merely 1/4" shorter then the 15s!!
So it looks like all one needs to do to go from 14 to 15rnd is obtain a 15's base,check spring leangth,adjust(if needed,I have not tested yet),assemble and go. :shock: Bottom "window" will not match but :roll: .