Yeah, and then if you are dealing with something like a 220 Swift, for instance, you have to decide whether to toss the brass, inside ream, or outside turn the necks. (or whether it is worth it, at this point) You get a lot of brass flow in certain cartridges. So, you have to be careful about your over all length and the possibility that the necks are being crimped when chambered. There is also a possibility that you have developed a "donut" inside, if you have already worked the necks. Just to clarify, you mean .0010 total neck tension, not wall thickness?
I don't believe you could possibly put enough neck tension on any type of case to cause a dangerous situation as long as the load is safe. Think about how firmly Factory ammo is crimped, I'm willing to bet that even grossly undersized brass wouldn't hold a bullet as much as those types of crimps. I've seated bullets into cases that were sized w/o expander balls in FL sizers which actually made the bullet stretch the neck when seating and created quite a bit of neck tension. Those bullets are easier to pull than crimped rounds.
That is true, to a point. IF you start your load development with X amount of neck tension and work up from there you can produce safe consistant loads most of the time. Only problem with excessively heavy neck tension is that it is seldom consistant from one case to another so that is a problem.
My warning was in reference to taking an established load and increasing the neck tension on that one load, pressure will increase significantly over the previous load.
But I would agree mostly with your comment.
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It seems to me that there is a relationship between a tight necked chamber, and not so tight, but thickened necks caused by repeat firings. All things being equal, same load, (same reamer) but tight neck versus standard dimensions, the tight neck (chamber) should show more pressure signs? Whether this is achieved by tooling, or by thicker neck walls, the results could be the same.
In other words, I have a rifle with a tight neck. A very safe published load is a hot load, in this rifle. You could say that every rifle is different, but I choose to believe that the flat primers are/were (mostly) due to the tight neck.