I worked for sheriff dept. in my small town. we use are own guns. and i was the only one with a 10mm. and everone keep asking what i would do in case a i ran out of ammo. and my partner had extra clip of 40. we was having inservice. and on range day. i fired a clip of 40. it was a g1 20. there wasnt any diffrents. i could tell the group was just a little lower. i dont know if id try this on a everday base. but deff, would if had to. but wouldnt this be the same as using the 38 special in the 357mag. a 158gr bullet load the c.o.l in 38, is 1.450. the 357, is 1.590. on the 40s&w, 180gr c.o.l 1.125. the 10mm, is 1.260. that is almost the same so wouldnt it be just as safe. or am i missing something. with ammo getting harder to get i might haft try it again.