I use the 7 round mag as is. I have Pearce Grip extensions on all of my 6 round mags. No issues. Only thing I found was that the mag base lock provided by Pearce was a little thin and I got extra ones that you would find on the 7 round mag from Kahr. They are thicker and hold the grip in place better and tighter. With the thin base locks, the grip had a tendency to slide off with the slightest pressure.