The springs will work in both the five and seven round mags. You may have to clip off a bit more in the five round mags then the seven. Here is the link to the thread:
XDS Light Strikes - Page 2 - XDTalk Forums - Your XD/XD(m) Information Source!
Here is what the guy that figured it out had to say, these are two different posts.
Guys name is toolman on the forum:
I've had a lot of trouble with out of battery primer strikes with my XDs 45, I've done a lot of testing, Customer Service was of no help whatsoever, but I finally solved my problems.
What was going on? I know this sounds crazy and some of y'all will say IMPOSSIBLE! Here it is, it's weak mag springs.
No way? Put one of these in each of your 5-round mags (yes they will fit) and see if all of your troubles don't disappear:
Trip Research MS-14C048 replacement spring (sorry couldn't get a link to work)
Tripp Research Inc. 1911 Magazines
See if I'm right, heck, prove me wrong if you can.
Another post of his:
The 1911 pistol smiths and 1911Tuner call this "inertia feed". The nose of the top cartridge in the mag is trying to move up and out of the mag while the slide is coming forward and the bottom corner of the breech face drags across the nose of the top cartridge in the mag. The top cartridge in the mag is what holds the slide out of battery.
New Tripp Research springs in my mags has my XDs feeding slicker than frog snot!
Now she'll feed limp wrist, loose grip , right side up, upside down, sideways, any way I've tried!
This is a long read about 35 pages but there is some very good information and real problem solving going on here. I wanted to get rid of my XDs .45 after my first range trip, but now after my fourth range trip and about 500 rounds it is running perfectly, and a good cleaning and Froglubing I really like this .45 and will carry it everyday. I hope this helps some of you with any problems you may be having.