This is the straight dope on gun springs. Spring steel takes a set. Meaning that the spring steel is already tempered before the spring is folded into whichever configuration is needed for a particular function, and that is the key. Now, if you load a magazine to full capacity and leave it,you ar changing the form of the spring through constant pressure over time. Add in environmental effects such as oxidization and heat and you set the spring. You can't take a spring from a magazine, stretch it open and put it back in the magazine. The stress placed on the spring from compressing and extending the spring causes weakness. At that point, you just need to replace the spring.
Now, if the gun is a Mauser, why don't you just use a stripped clip, and if it's something else, see if brownells offers a external magazine kit for it. I know they do on the Remington 700's.
The method walker told you to use for closing the bolt on a full magazine is the correct way. Mausers use 4 in the magazine.
Now a caveat. If you were to load a magazine a 2/3 full level, you can get away with it for years. I did an experiment with Ak magazines and 1911 magazines several years ago. The springs were still good 2.5 years after loading when using 20 on 30's for the Ak and 4 in 7's on the 1911. That's kind of a cheaters way of keeping magazines loaded without ruining your springs.
Also, to whoever posted about the truck springs, remember that they are being used at factory tolerances when there is no load on them, but leave your truck with a bed full of concrete for a year, then tell me if you're replacing springs or not.
springs,