from what i have seen, one of the main causes of failure, magnum or non-magnum is due to lack of cleaning and maintenance. crud and rust will help any spring or extractor weaken over time. I recently had a bolt sent to me to replace the extractor and I did a detail cleaning. From a picture of the rifle the owner sent to me, he knew how to wipe down the exterior of the rifle with a cloth but things ended there. The amount of crud in the bolt face, extractor, along any fine edge and inside the bolt itself, kind of makes you wonder what the chamber looked like and if he needed both hands to open the action after firing or just hit it with a stick. Should of had him send the whole rifle in so that i knew it was clean and he wouldn't be back to forcing the action open with every round and tearing up his new extractor in the process.