Here's a new challenge to think about. I have reloaded for my M70 in 7mm Mag for a number of years now and have never had the problem I'm about to describe. A friend of mine also has a 7mm Mag but in a Remington 700. He's fairly new to rifles and I have been happy to build some bullets for him. But we ran into an issue.
I recently loaded up 20 rounds for him. 16 of those 20 rounds fed no problem, the other 4 however did not feed quite properly. He was able to push the bolt all the way forward but only barely could he close the bolt.
We made some measurements of the brass. We found that the measurement from the case head to the start and end of the shoulder were somewhere around 0.050 - 0.060 inches longer on the rounds that would not feed versus those that would. The overall measurements even for the rounds that would feed were slightly longer than specs in my loading manuals. Not by much, but some. Obviously for the rounds that did not feed, they were quite longer than what would be expected. The OAL for the brass was under the spec of 2.5" for all cases measured.
Now this was on brand new Remington brass which I ran through the FL resizer. For giggles I had some brass waiting to be resized and I ran those through after ensuring the die was setup properly. Same results, it looks like my resizing die is not bumping the shoulder properly.
Do sizing dies wear out? Was the die perhaps just bad to begin with but it took loading for my friend's Remington to find out?