Well regardless of what may have been posted before it is standard procedure and critically important to gauge a rifle when changing the bolt. Have thousands of guys done it without gauging and got by with it? Yes, but its such a minor process there is no excuse for skipping it, even if you have to pay to have it done - that's what I do because its so seldom that I would change a bolt. I really don't shoot that many rounds and I have a number of rifles, so I never wear anything out or break anything.
Although, just yesterday I had to put a new spring in an AR. When I made it, I used a refurbished M16A1 stock, tube, spring and buffer. I assumed the spring was new/good but that was a mistake - I should have put a new one in. So I was shooting some fairly hot IMI 77gr last week and popped a primer so that's when I started looking for anything in the gun that may have abetted that process. When I tried the new standard recoil spring and saw how much stiffer it was than the old one, I knew I had found at least part of the problem. The other part is this ammo is known to blow primers particularly when the set-up is iffy, like mine was.