Originally Posted by Desert Fox
Sorry Coyboy, I was out of town on vacation for a week. Sorry about the picture, my daughter's camera that I'd been borrowing can't focus that close. Extraction was tight. The case head was overblown that I have a hard time removing the case from the bolt. The case head wedges itself around the bolt rim with the extractor claw holding the case. The primer was nowhere to be found. Talked to Hodgdon technical support and was told that any sphirical powder irregardless of brand has a tendency to have higher pressure when subjected to higher outdoor temperature. My load development was done during winter and I'm confident that it will still be good during summer since I'm still 2 grains below the listed maximum. Boy was I wrong. Hodgdon told me that it probably reach 70,000 psi. This was an eye opener for me. I'm using Federal Gold medal Brass, Federal Match primer, 45 grains of BLC-2 and 168 grain Nosler J4 Competition match bullet. COL 2.796
Something isn't like you thought it was. I don't know what isn't, but something isn't. I'm basing that conclusion on the following analysis.
That load (.308Winchester, Nosler HPBT J4 bullet seated for 2.796 COL, 45.0g BL-C2) models in QuickLOAD at 53,975 psi which is well below max (60,191 psi) even at +122F (the hottest setting available in QuickLOAD). At 90F it the predicted pressure is 50,802 psi, and at 60F it's 48,089. That's enough margin that I don't see how you could have had what you think you had in usable brass and gotten even the faintest hint of over pressure.
So something was not "as designed".
The usual suspects in a case like this:
A different powder than you think you had - lot to lot variatons shouldn't cause a problem for the load described. Even H335 "probably" wouldn't show signs at that weight. I have to move up the list to H322 or faster powders to get pressures over 70,000.
Brass that's too long so there is neck constriction but you should have felt that when chambering.
A cartridge that didn't get the bullet fully set back to the proper COL so it's jamming in the lands but in this case you would still not be much over max, or recoil from previous shots moving the bullets forward.
A fast powder like a handgun powder left in the trickler by accident so several tenths of a grain of that powder (It wouldn't take much of something like W231) got into the load.
Or similar almost freak circumstances.
There are probably more but I don't see how the load you think you had, loaded into brass that wasn't defective, could have caused any pressure signs at any outdoor temperature you are likely to have encountered - so something was different. I don't know where Nosler got their 70,000 psi number form but I can't get anywhere even close to that number for your load.
A freind of mine brought over a motor cycle that wasn't running - it was a little two cycle Yamaha 50cc bike - his daughters desert bike (this was in the early 1970s). He told me all the things he'd checked. So I ran it up on my motor cycle service ramp (I had 7 of them at that time - 5 dirt bikes and 2 street bikes) and started to take the float bowl off the carb to check for a plugged idle jet. He said, "I've already checked that". I said, "Herb, if everything you said was OK, was really OK, it would run. So I'll start here because it's the easiest thing to check and I can already see fuel dripping so I know the filter isn't plugged and it makes a firing noise so there is spark. The idle jet was plugged solid. Cleaned it out and the thing ran just fine.