Try to find an older mag that is all metal. The new ones have the plastic on the bottom. I have found that they are not nearly as reliable as the older ones. If you have an old gun shop or a pawn shop around they should have some laying around. I have not had good luck with the new clips, on the other hand, I've had no problems with the older ones.
You do need to clean the crud out of them from time to time though. The mag should hold 4 and function flawlessly. You can put one in the pipe too, but if you can't hit 'em with 4 I don't think the 5th will help you too much.
Try to spray a little Rem-Dri Lube in the mag spring, see if it helps.
