You're right it will loosen up as you use it.
Also I use an UPLULA speed loader and it makes loading magazines a breeze. I shoot 40 S&W and know your pain Here's a link http://maglula.tripod.com/
Just picked up my first Glock; a Glock 30 SF. Had a great time shooting it today but man o man the double-stack mags are really tight. I assume they will loosen up over time but any hints or suggestions on making loading all ten rounds of .45 easier.
The G30 mags are a b*tch to load; moreso than any other mag (even other Glocks) I've used. It's such a tight fit, upon loading mine, the ninth round shell would actually get bent by the 10th round being pushed on it. And then, when the mag is fully loaded and I rack the slide, the slide will interfere with the 10th round and make a nice slot all the way down the shell. I've never had a problem while shooting it, though. When I get a new mag I will load nine and leave it in the safe for a week or so. Makes it a bit easier but they're still very difficult.
When I am at the range I just load nine, unless I want my thumbs pulsing in pain after a few mags.
To "break in" a magazine, the spring has to cycle. Simply loading the spring by filling the magazine with ammo and letting it sit is the same as if the magazine sat empty. Only over time and use will the spring "loosen up". My suggestion is get a loader and load/unload the magazines a few times every comercial break next time you are watching tv, before you know it that 10th round won't be such a pain.
Thanks for the input everyone, guess I will just have to spend more time shooting! I appreciate it.