Re: Excessive Headspace!
I'll share a story/experience. Take from it what you will.
I built a big heavy 6mm-284 once. It had all the high dollar stuff so I expected it to hammer.
It was initially a lemon. Just like lightening, it never struck twice in the same spot. . .
After considerable head scratching and fussing it was pointed out to me by one of my employees that the headspace was a "red one" on the tight side. The barrel was fluted and during final assy I had to give it an extra grunt to get the flutes timed up right. This was enough to cause a slight interference when rotating the bolt into battery on a loaded chamber.
We pulled the barrel, squeaked the chamber a smidge and put it all back together and it began splitting hairs on paper right away. I had a really, really, really hard time accepting that's all it was but it was the only thing that we changed so it was/is tough to argue with. I've made it a point since then to ensure the cartridge has enough room to sit "tension free" in the chamber ever since and this particular demon has never surfaced again.
Take from that what you will.