It's normal, the springs are new and will loosen up as the mags are unloaded and loaded through cont'd use. Some will tell you to leave the mags loaded, but this will not wear a spring. It is only through compression/decompression cycle that a spring is worn.

 

My 2 standard issue 8 round H&K .45c mags were ridiculous to load for the first couple hundred rounds and they have since eased up a little. I just noticed it the last time i went to the range (the round count for my pistol is just under 1000) I also use two ten round mags as well, from the start they were easier to load than my eight rnd mags. I've never had one issue with any of them ever. Not to be a d*** but fingertip push ups and/or using stress relief squeeze balls should relieve or lessen this perceived issue until the mags are broken in. (finger/grip strength) IMO :6200:

 

The spring will relax some and be easier to load.

I notice the springs on my 10 shots mags seem to be weaker than the 12 shot. I have a few 10 shot mags that will not engage the slide stop reliably. A simple spring stretch fixes it (temporarily) but they load and function fine.

 

A simple spring stretch fixes it (temporarily)

I've always heard this was a no-go when it comes to springs, that it would in effect ruin the spring. Someone with more knowledge please chime in. Also, the uplula is very nice if you're gonna be at the range for a while.

 

Get an UpLULA universal pistol loader. Works great on 1911's, Sig's and now HK's that I have. Just don't lose it because you really will not want to return to the old way.

 

Since the spring compressed some ( not engaging the slide stop ) stretching it is a temp fix.
We are talking and inch ( or less).

It does no more harm than the spring not performing as new (compressing and taking a set).