I'm using one in a single stack, I had to work on the spring before the mag would work. I believe they have or did have some forty mags with a removable base. If I was going to buy another this is what I would want. Also I've had good results using CMC Shooting Star 45 mags in my forty single stack if you have one you might want to try it.
Regards,Bob Hunter.www.huntercustoms.com