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Sako 85 Finnlight 270 blew up

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Horsemany View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Horsemany Quote  Post ReplyReply Direct Link To This Post Posted: October/21/2009 at 17:56
Originally posted by Monster Monster wrote:

Normal case separation would not have caused that bad of a reaction. There had to be some insanely high pressures in that round.
 
I tend to agree.   The rifle should be designed to handle a ruptured case better than that.  It's interesting the barrel looks unharmed.  I saw a Ruger with a case head seperation at my local club 3 years ago and it basically amounted to soot around the receiver vent hole and a little on the stock.  The rifle was fine and shot the rest of the day.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote lucytuma Quote  Post ReplyReply Direct Link To This Post Posted: October/21/2009 at 17:58
Thanks for posting this information, it's a great reminder to us reloaders of what can possibly happen.  Your misfortune may save one of us reloaders in the future, I'm glad your ok.  The rifle can be replaced, your eyes, fingers and life cannot, no matter what the outcome is with Sako, I think you already are very fortunate to not have been terribly hurt.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote RifleDude Quote  Post ReplyReply Direct Link To This Post Posted: October/21/2009 at 18:38
Originally posted by Monster Monster wrote:

Normal case separation would not have caused that bad of a reaction. There had to be some insanely high pressures in that round.
 
Not true.  I've seen rifles with the entire bottom metal blown out due solely to case head separation.  I've heard reports of extractors blown completely out of actions due to case head separation.  This is the reason some action designs such as the Remington 700 have completely enclosed, counterbored bolt heads that extends into the chamber end of the barrel.  The Sako doesn't have an enclosed bolt face, so in the event of a case head separation, the rapidly expanding gas is vectored out the bottom left side of the bolt face.  Even though the round may have been within normally safe pressure limits, we're still talking about more than 50,000 psi here!  The gas has to go somewhere, so it travels the path of least resistance, which on the Sako is down through the magazine and along the left side (from the shooter's perspective) bolt race.  This would explain why it blew the bolt shroud off, because the shroud is blocking the open end of the bolt race.  The amount of damage caused depends on the action design and the amount of peak pressure involved, so no two circumstances will necessarily have the same end results.  The fact that the barrel wasn't damaged supports the idea that it was caused by case head separation.  Seeing the brass will tell the story.  Usually the brass forward of the web ahead of the rim will still be in the chamber if it was caused by head separation.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ccoker Quote  Post ReplyReply Direct Link To This Post Posted: October/21/2009 at 18:57
As I stated earlier, I am very happy to have fingers and eyes intact

i had a nice bonus hit the bank on Friday so it allowed me, well, the wife allowed me :) to get another bolt action in time for deer opening weekend in a few weeks.. (the 700 LTR I posted about) 

the bolt is stuck in the gun, I tried to tap on it for a bit with a hammer, no go
 
interesting that Ted posts about the excess gas going low left, my left hand was around the mag well and was numb for several days

at this point, I am going to wait to hear from my contact who may be able to help before sending it in... 

I will be pleasantly surprised if they replace it...
if not, so be it
I am lucky to be able  to type this ....
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Post Options Post Options   Thanks (0) Thanks(0)   Quote RifleDude Quote  Post ReplyReply Direct Link To This Post Posted: October/21/2009 at 19:08

Notice also that the bolt stop release button was blown off the receiver... which is along the left side of the receiver, extending into the left bolt race.  It and the bolt shroud were blocking the path of the escaping gas pressure as it traveled along the left bolt race.

You truly are very lucky to be unharmed by this incident, Mr. Coker!  I'm very glad to hear this!
Ted


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Post Options Post Options   Thanks (0) Thanks(0)   Quote Kickboxer Quote  Post ReplyReply Direct Link To This Post Posted: October/21/2009 at 19:11
You had an angel on your shoulder on that one.  WOW.  Very glad you are able to write about this...
 
Be careful. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote RifleDude Quote  Post ReplyReply Direct Link To This Post Posted: October/21/2009 at 20:25
Originally posted by Kickboxer Kickboxer wrote:

You had an angel on your shoulder on that one. 


No doubt!  I don't see how in the world the bolt shroud missed your face!
Ted


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Post Options Post Options   Thanks (0) Thanks(0)   Quote RONK Quote  Post ReplyReply Direct Link To This Post Posted: October/21/2009 at 20:44
 I shuddered when I saw the bolt shroud, too.
 
 What is all the yellow discoloration on the stock (left side of receiver, and in the mag well?) Atomized brass?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Horsemany Quote  Post ReplyReply Direct Link To This Post Posted: October/21/2009 at 20:55
Ted if you're right that makes me think less of Sako's in general.  To send the bolt shroud/firing pin assembly straight back at the shooter is less than desireable.  I have only seen one other case head separation so I'm no expert.  The one I saw was almost a non event and shooting resumed a few minutes later. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote RONK Quote  Post ReplyReply Direct Link To This Post Posted: October/21/2009 at 21:04
Originally posted by Horsemany Horsemany wrote:

Ted if you're right that makes me think less of Sako's in general.  To send the bolt shroud/firing pin assembly straight back at the shooter is less than desireable.  I have only seen one other case head separation so I'm no expert.  The one I saw was almost a non event and shooting resumed a few minutes later. 
 Well, I can't think of any bolt rifles that would throw the bolt shroud/firing pin assembly anywhere other than back at the shooter, given enough pressure.
 I think Sako should get some credit for apparently venting the gas as it did, to bleed off much of the pressure into the mag well before it ALL accumulated within the bolt proper before perhaps REALLY coming unglued under tighter confinement.
 
(But I don't really know anything about Sakos; just speculating based on what Ted and others are saying...)
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Horsemany Quote  Post ReplyReply Direct Link To This Post Posted: October/21/2009 at 21:09

What I saw must've been an anomaly.  It just blew soot out of the vent hole in the receiver.  The old case was taken out (in two pieces) and after a few people inspected it they shot it.  I'm sure there are varying degrees of kaboom based on pressure and design.  What I witnessed must be the best case scenario.  The one I saw was a Ruger MKII in 270.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote RifleDude Quote  Post ReplyReply Direct Link To This Post Posted: October/21/2009 at 21:36
This Sako exhibited what can happen with any controlled round feed type action in the event of case rupture.  With half of the fence surrounding the bolt face milled away to allow the case rim to slide under the extractor, essential for CRF, it provides a directional path for gas to flow back into the action.  The same can happen with ALL CRF actions -- Mausers, M70's, Rugers, etc.  The only style of action that is essentially immune to this is a completely enclosed bolt face, with the barrel shank counterbored to allow the bolt nose to fit inside it, such as on the Remington 700.  An enclosed bolt face contains the gas flow and doesn't allow it any pathway to shoot back into the action.  So, in dealing with gas, you can either direct it or contain it.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote RifleDude Quote  Post ReplyReply Direct Link To This Post Posted: October/21/2009 at 21:41
Originally posted by RONK RONK wrote:

 Well, I can't think of any bolt rifles that would throw the bolt shroud/firing pin assembly anywhere other than back at the shooter, given enough pressure.


Correct.  Bolt actions in general essentially consist of a tube inside another tube with the end of both tubes facing the shooter's head.  There's no other way around it.  One of the worst designs in dealing with gas pressure in the event of case rupture is the Pre-64 M70.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Horsemany Quote  Post ReplyReply Direct Link To This Post Posted: October/21/2009 at 21:50
That's correct on the pre 64.  Had they left the flange on the bolt shroud like the Mauser 98 I believe they could be declared.....perfect.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Monster Quote  Post ReplyReply Direct Link To This Post Posted: October/22/2009 at 00:10
The reason I was thinking not normal case speration because I know of someone who has had case speration in an encore and I would think that a sako bolt action would be a lot stronger than an encore
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ccoker Quote  Post ReplyReply Direct Link To This Post Posted: October/22/2009 at 08:40
after more discussion with others I think I may have had case head seperation with the Federal brass due to excessive pressures

I may have simply gone over that edge

I was not trying to get the last few FPS, it was that according to Barnes and others they tend to group best when driven hard...

perhaps a lesson for those that reload and get obsessed with speed

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dale Clifford Quote  Post ReplyReply Direct Link To This Post Posted: October/22/2009 at 09:43

Is there any possible chance that you grabbed a 308 round, which will fit in a 270 chamber. Seen a similar instance of this. What powder are you using?

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Post Options Post Options   Thanks (0) Thanks(0)   Quote ccoker Quote  Post ReplyReply Direct Link To This Post Posted: October/22/2009 at 10:11
I haven't got the bolt open, I guess anything's possible, though I was using one of those 20rd clear plastic cases and each round had me mark it with a sharpie with the powder charge... so, I would have had to be a real idiot..  and, that's completely possible

there was a hole in the target at 100 yards, albeit about a ft high (indicating high pressure)

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dale Clifford Quote  Post ReplyReply Direct Link To This Post Posted: October/22/2009 at 11:21

in one instance the 308 bullet was swaged down,shot hit the target, and acted like a normal round, the other instance, gave your results.

are you using a med. ball powder?? Do you load for any handguns.?? or shotguns.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Shenko Quote  Post ReplyReply Direct Link To This Post Posted: October/22/2009 at 11:48
Did you mic and weigh the bullets you pulled, and the other bullets from that box?
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