More good advice from Kirby.
You can't apperciate how fast the pressure will spike once it gets so high and the destruction it can cause unless you have seen it , I've never seen it first had but I have seen the coroners photos of the scene and the body , that has to say enough right their !!!
on factory guns I generaly start to see slight shiney spot on the case first then the bolt lift very close or at the same time and if you get a soft batch of primers you may see slight cratering first , this to me is pleanty hot enough.
I know a guy that has a gun thats welded shut from one shot !!! ,he worked up a load for his 22-250 on a cold spring morning to get ready to shoot the ground squrrels when it got warm. His load was running a 55 gr Ballistic tip out at over 4000fps from a 24" 1-12 Douglas barrel, he diden't make it out to shoot till mid June and the temp were in the low 90's , first shot the gun went off and he look at us as we looked at him with that "what the hell was that" look on our face when he tried to open the bolt it was stuck solid and coulden't be hammered open !! upon inspecting the gun we removed the scope and saw that their was a crack in the front reciever splitting it between the scope base mounting holes. Several custome gun builders looked at it and guessed that the pressure was in the 80,000-90,000 psi range !!!
Anyway if they on't shoot well that seems like a great reason to rebarrel the gun right?