And as I have said before they will also work in the new PC9, if your not shooting IDPA
I have a 18.9 Limited that I shoot USPSA, (I have 20 Canada made mags)
Also I have the newer Pro Custom 9 and all 20 mags WILL run with the DP extensions.
If shooting IDPA the mag needs to be almost level at the bottom of the mag well. this can happen with the
OEM mag that comes with the PC9 and http://www.dawsonprecision.com/ProductDetail.jsp?LISTID=80000064-1388517802
Please, I have been looking/working on this for around eight months... You can file some of the after market mags that may or maynot run.
hope this helps some of you that are having the PC9 mag issue.