I assumed the magazines from the 9mm 3.8 compact would be the same mag I use in my fill size 4.5 XDM 9mm. I was at Gander Mountain and the associate said he didn't think they interchanged. He was running the paper for some guy so I didn't play with them. I did a search on the site and saw the question posed for XD to the XDM of the same type and caliber. I didn't see a thread on this one, maybe because its so common sense. I know a 13 rd will not fit in a full size, but a the full size 19 rds..