Not a great way to begin a thread on load development but....
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farmerjohn
Gold $$ Contributor
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The bolt was still in the lock position. I took a few more pics so y'all can see. Side pic shows it locked down. The end is where ejector is and the other one is a close up of the end of the bolt.
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Thanks. Appreciate it. Glad no one else was near us thankfully. Never want to have that experience again. Also reinforced wearing safety glasses is mandatory
wkdickinson
Gold $$ Contributor
I really doubt that if you seated a 30 cal bullet, you could even get the action you close, because of the size of the neck.
Jager
Gold $$ Contributor
Glad you and your son are okay.
Wrong powder, wrong charge weight, wrong bullet, or obstruction in the bore are the obvious first thoughts.
If you dismiss those, you're kinda down to a manufacturing defect in the rifle - which would be highly unusual in the first place, and especially since you had already put a fair number of rounds through the rifle. Or... a fairly uncommon phenomenon called Secondary Explosion Effect. Though rare, S.E.E., when it happens, is an unexpected pressure excursion which is usually catastrophic. It is almost always seen in larger capacity cartridges with lighter loads of slow-burning powders.
If I adjust Quickload so that it's seeing 2801 fps out of a 22" barrel with a 160 gr. Nosler AB in front of 57.1/H4831SC - your last load before the blow-up - it's showing chamber pressure of 58.4K and a load density of 95.3%.
The next increment of 57.4 would have taken velocity to about 2816 fps and chamber pressure of 59.4K.
On its face, that load density and that chamber pressure aren't such that they'd give many guys pause. But max pressure in the 280AI is 65K psi.
You were a little light.
Wrong powder, wrong charge weight, wrong bullet, or obstruction in the bore are the obvious first thoughts.
If you dismiss those, you're kinda down to a manufacturing defect in the rifle - which would be highly unusual in the first place, and especially since you had already put a fair number of rounds through the rifle. Or... a fairly uncommon phenomenon called Secondary Explosion Effect. Though rare, S.E.E., when it happens, is an unexpected pressure excursion which is usually catastrophic. It is almost always seen in larger capacity cartridges with lighter loads of slow-burning powders.
If I adjust Quickload so that it's seeing 2801 fps out of a 22" barrel with a 160 gr. Nosler AB in front of 57.1/H4831SC - your last load before the blow-up - it's showing chamber pressure of 58.4K and a load density of 95.3%.
The next increment of 57.4 would have taken velocity to about 2816 fps and chamber pressure of 59.4K.
On its face, that load density and that chamber pressure aren't such that they'd give many guys pause. But max pressure in the 280AI is 65K psi.
You were a little light.
Just looking at the pictures and the fact I'm not familiar with CA rifle it looks to me like like the case failed and blew the extractor out. This allowed the gasses to overpressure the action behind the barrel and in front of the lugs. The action failed and released the barrel. There are normally holes in that region to vent but I'm not sure just how well the work in a catastrophic case failure. The velocity is low because gas was released during bullet travel. The barrel pressure was lower.
Best 1st guess as to cause is severe overpressure. Loaded same time as your son's load? Did you recharge the powder measure during reloading?
Best 1st guess as to cause is severe overpressure. Loaded same time as your son's load? Did you recharge the powder measure during reloading?
wkdickinson
Gold $$ Contributor
Have talked to Christinson about this? To see a reciever ring blown out like that, scares the shit out of me!
46and2
Silver $$ Contributor
Christensen arms told me reloading for their files voids their warranty!!!!
Their reamer was so worn at the end of the neck that i had to neck turn perfect brand new Lapua 300wm brass.
I will never ever suggest anyone buy anything from CA. I learned my lesson. The only thing left of my Ridgeline is the bottom metal and action. And after reading this thread I'm rethinking using the action anymore.
Thanks -glad we are no one else was impacted.
We only had the one powder (8lbs of H4831SC) out when we were putting these rounds together and all of the rounds that we loaded (60+) were the same powder, so I would say very low probability it was the wrong powder.
I had two other un-fired bullets from that same string (57.4gns) which were loaded to the 57.4 charge weight. I pulled the bullets from those cartridges and weighed the powder after this even. They were both 57.4 grains so I feel pretty confident these rounds weren't overcharged. I had three more with a higher charge load. I can also take those apart and see if they are 57.7gns.
I initially thought it was a squib load (obstructed barrel), but we checked the target and the number of holes matched the number of rounds fired (except for the blow up one of course). In addition, we registered 2800fps on the last 57.1 round which I'm assuming we wouldn't have seen if the round had never come out of the barrel, so I think it highly unlikely there was an obstruction because of that.
Great info on the SEE. Wasn't aware of that. Would you think that this would have manifested itself with the other rounds that I shot before this since those rounds had lower charge weights or is there some intersection between charge weight and volume that triggers SEE? I'll do some more research on it as you piqued by curiosity (always good to learn)
Appreciate you running that through QL. Just to make sure I understand - based on QL, the loads I was shooting shouldn't have exceed safe levels (not counting out SEE). That jives with all the research that I did before deciding on the charge weights. I assume the last comment that I was a little light meant I was below the Max/Dangerous load threshold. Just want to make sure I understand.
Again - thanks for the response. Really appreciate trying to understand what happened.
lawman29
Gold $$ Contributor
Excellent...
I use a RCBS charge master on a separate table so as to minimize any interference which could cause it to not measure correctly. I always calibrate both scales before starting. I don't even run the ceiling fan (seriously) as I've seen minute changes. I then double check the load weight with a separate scale to make sure it is consistent. Takes a little longer, but I'm doing low volume so not a big deal (plus safer).
I'm with you on the overpressure. I'm just at a loss as to what caused that. See my above responses on questions regarding obstructions, powder, etc...
Not afraid to take accountability if I hosed something up. Just want to make sure I don't have a similar issue in the future
Not yet but I will this week.
I assume the excessive bolt thrust was from over pressurization. Any thoughts on why?
It was virgin brass so straight out of the box from Peterson. Given their reputation, I would be super skeptical of something in the brass. I did have another piece of brass from them that I couldn't get in my shell holder on my primer seater. It was the only one like that. I set it aside. We micrometered hat piece of brass and it was wider at the base then the others, but all of the charged rounds fit in the shell holder else we wouldn't have been able to get the primers in them.
DShortt
Gold $$ Contributor
Excessive bolt thrust can be caused by such things as neglecting to remove the case lube or too fine a finish on the chamber walls.
Edit to add - the SEE scenario others have mentioned is another possibility for excessive bolt thrust. I don't place a great deal of confidence in that theory because it's a subject widely disputed and apparently not repeatable under test conditions.
The case needs to expand and 'stick' to the chamber walls. If it doesn't, it slides back on the bolt face when the pressure builds during firing. I see cracks in the bolt face, the extractor blown out and the ejector appears to be stuck back in the bolt head. The firing pin also appears to be jammed back and stuck, but it's difficult to tell in photos.
A picture of the case head would be nice to see if it's available.
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lawman29
Gold $$ Contributor
The first post has it....
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