I'm not trying to be argumentative, I think maybe I'm not following what you're saying and am trying to understand.
So a barrel is crap unless every shot from a cold bore goes to the same spot and every hot bore shot goes to that same spot?
And how big does that spot have to be before the barrel is "crap"?
And if the barrel has to shoot to the same spot regardless of how hot it is, why stop at 10? Why not 30 round groups?
You seem like a guy who shoots a lot, I'm just trying to follow what you're saying.
So I'll first answer your questions and then post the why.
Yes, a barrel is crap unless every shot goes to the same spot. How could it not be? If you are trying to hit a target, ie deer, rounds that group really close together but not in the center are useless.
As for the size spot it depends. For
my big game rifles 1.5 MOA 10 round groups at 100 yards is about the limit. That's my general rule because every normal deer clambering is capable of killing deer out to around 600 yards. For the LR specific guns I want 1 MOA max for 10 rounds. Work M4's with match ammo I replace the barrel when it hits 2 MOA for 10. That's day in and day out.
As to why not thirty rounds? Because I've tested it. A lot. Statistically 10 round groups will show where something like 98% of all rounds fired will land. 20 and 30 round groups just send more ammo through the same hole in the target.
What I'm saying is that what is termed "cold bore shift" or the "cold bore shot" impacting differently than the follow on shots, isn't because the bore is "cold". Neither is "walking" as the barrel gets hot. Now if there is residual stress with the barrel/action/bedding or something else mechanically wrong with the gun, then yes you could see that. But given a properly built barrel and gun, any shift you see from cold bore or "Walking" from firing more than ______ amount of rounds, is from cold shooter (not getting NPA, press, etc) or the natural dispersion of rounds.
