Gas-Relief Holes/Blown Case-Heads?
I was perusing my copy of "Rifles Of The World" when, in the exposition on the French Chassepot, I came across a "discussion" of allowing gases from a blown case-head or ruptured case to escape the chamber. This got me to thinking (no laughter, please):
Regarding modern factory-load or military-load cartridges, how often does this "blown head/ruptured case" disaster happen?
How do rifles like my Remington 700 VLS, or my 48 Yugo Mauser, or my 98K Mauser, or my WWII '03 Remington, or my 1917 SMLE, or a Finnish Mosin-Nagant guard against this---or DO they? Is it simply the case that the manufacturers (hopefully) build the actions strong enough to withstand such an event?
When a case-head blows, or the case ruptures, what happens to the gun? I.e., does the chamber crack, or does the bolt split, or does the gun make some sort of Godawful noise? And how serious is such an event to the safe operation of the gun?
Would having a case-head blow or having a case rupture in a bolt-action gun that's had a scope mounted on it be enough to damage those little screws holding the scope-base on the front of the receiver? The reason I ask this is that I can't imagine a threaded screw being as strong as the solid metal that was there before you drilled and tapped the receiver.
And, finally: Is there any particular cartridge in the family of 8mm Mauser, .30-'06, .303 British, .308 Winchester, or 7.62 X 54R that would be more susceptible to such failure?
Many questions, I know, but it seems to be a very complex subject!
Regarding modern factory-load or military-load cartridges, how often does this "blown head/ruptured case" disaster happen?
How do rifles like my Remington 700 VLS, or my 48 Yugo Mauser, or my 98K Mauser, or my WWII '03 Remington, or my 1917 SMLE, or a Finnish Mosin-Nagant guard against this---or DO they? Is it simply the case that the manufacturers (hopefully) build the actions strong enough to withstand such an event?
When a case-head blows, or the case ruptures, what happens to the gun? I.e., does the chamber crack, or does the bolt split, or does the gun make some sort of Godawful noise? And how serious is such an event to the safe operation of the gun?
Would having a case-head blow or having a case rupture in a bolt-action gun that's had a scope mounted on it be enough to damage those little screws holding the scope-base on the front of the receiver? The reason I ask this is that I can't imagine a threaded screw being as strong as the solid metal that was there before you drilled and tapped the receiver.
And, finally: Is there any particular cartridge in the family of 8mm Mauser, .30-'06, .303 British, .308 Winchester, or 7.62 X 54R that would be more susceptible to such failure?
Many questions, I know, but it seems to be a very complex subject!
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so many questions so little space to type in[:o)][:D] kidding ya!
That hole you see on the side of the receiver is the gas releif hole in most any action. Your 700rem has it on the right side, as do most other modern rifles. The majority of the gasses will find their way down the magazine well and out the bottom of the rifle around the mag plate and trigger guard. A lot of the gasses will initaily try to find a way out the back of the action, around the bolt, and toward you eyes and face. This is the point at which many of todays rifles have been designed to further funnel the gasses down to the mag well. Many design changes have been made in the past 30yrs +/- to make this happen. Ruger 77 actions, according to an article I read somehwere, are one of the best designed actions available for catastrophic damage control. Mauser 98 actions are heralded as being one of the strongest actions made also ( I won't persoanly subscribe to that unless THE action I HAVE is tested for strength and hardness right in front of my own eyes) There are too many mauser actions with many many thousands of rounds fired in them with many barrel replacements, that I would not trust it to sit in front of my face and control the explosions of many of the currently available calibers. Most all actions have been designed to deflect the gasses that escape around the bolt/shroud area, and redirect them downward and outward away from the shooter. A search of action schematics would probably help a lot more than my explanations
When it happens, from what I have read and heard about, it will sound like a thunder crack right next to you. If it was the result of incorrect powder or an overloaded round, recoil will be greatly increased. If it was a thin case that seperated at the head, recoil should be the same or even less than usual. The locking lugs of the bolt. combined with the action should, I say "should", keep the bolt from implanting itself in your face, and the action receiver ring, barrel chamber, and stock will most likely do the giving. Cracked stocks are almost a given, slightly or severley burned fingers fon the trigger hand are common as well. Quite often the case head will come out with the bolt, but the remaining case will have to be extracted by beating it out or extraction tools, and sometimes the locking lugs will be "set-back". If you feel a ridged feeling when closing the bolt, that is the set-back portion you are feeling. That will no doubt have increased headspace as the bolt was forced rearward by however-many thousandths of an inch.
Most likely, in the case of the scope, the screws will be damaged. I have seen pictures of them completely blown in half with the rings still attached to each half, and they ended up 30yds away from the bench!!! I have also seen pictures of the barrel being completely blown out of the action, threads and all!! This instance was a 7mm rem mag fired in a 270wthby mag chamber, but gives you an idea of what a blown case can do to a rifle (and your face and digits) This was an oversized projectile VS undersized bore, and containing a magnum charge, so it is on the upper end of BAD SH!T that can happen.
In a case head seperation, the damage will usually be less due to the bullet traveling the bore and allowing some of the gasses to follow. That is in no way stating that a case head failure is nothing more than a nuisance, it is very serious as well. you will still get the escaping gasses anywhere they find to go, and remember they are several thousand degrees!!!
There is no family or caliber more susceptable to case head failures IMO, but the military rifles are more prone to "first firing" seperation of a case, due to some of the old mausers and militray bolt guns being wayyyyy too generous with their headspace dimensions. Any old militray rifle should be submitted for at least a go/no-go test before firing.
This is just what I have learned about KB's over the years,....I hope to never give a real world example. I have read several studies of the sequence of events when a case head fails, and read quite a few threads by those who have had the experience. That is where my info is coming from, and it is in no way based on blowing them up in a laboratory with measuring equipment attached to them to gain data. I am sure another member who probably has witnessed or had the displeasure of experiencing one will come along and correct and/or add to my information. Hope this helps,....and be sure to check headspace in your military rifles with any age on them.
why chase the game when the bullet can get em from here?....
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Run out of space JustC? Here is some more:
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[:I] too short?
why chase the game when the bullet can get em from here?....
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Just a side note about the Remington M700, they claim the cartridge head is surrounded by "three rings of steel" as Remington calls it, for protection from such an event, I assume.
Better to have and not need, than need and not have.<BR>0 -
Man oh MAN, this sounds downright SCARY....Especially since I collect and shoot old military rifles. I've got a '48 Yugo Mauser, a 98K German Yugo-refurbished Mauser, an arsenal-refurbished WWII Springfield, a 1917 Enfield, and I was contemplating a good Finnish Mosin-Nagant (like, say, an M39.) I never thought to have the headspace checked on any of these rifles, especially the Mausers (tho' I did have headspace troubles with the Enfield, and had the guys at the place I bought it replace the bolt-head, so presumably they checked the headspace on THAT one.) I guess I should now! 0 -
quote:Originally posted by SP Tiger
Just a side note about the Remington M700, they claim the cartridge head is surrounded by "three rings of steel" as Remington calls it, for protection from such an event, I assume.
Yes, they rarely have a "seperation". What happens with a remington is the action locks up tight As the bolt ring expands into the barrel recess, and your through hunting
(. Aa gunsmith I had a lot of them come in that way. poor design IMO. And of course too often the frustrated hunter up in the elk camp takes a stick of firewood and frams the bolt handle to open it and the soldered on handle comes flying off (another design flaw) ). A ruger, mauser, mod 70 etc. would have ruptured the case head, exited the gasses and you'd have gone on hunting with some work clearing the chamber. It can be a number of things besides overloads but that's usually the culprit. I've seen guns left outside at night propped agianst a tree that got a lot of dew in the bore cause it. Even ammo left in the sun can up the pressures. One other thing with handloads is not trimming cases and camming the long case into the chamber throat and pressing it into the bullet tightly.
Had a customer who brought in a blown Ruger 77 in 7 mag that he had called ruger about. It was a bad one and the whole magazine well had blown out. Shooter only had some scratches & cuts on his forearm. I looked at the ammo and pulled a bullet. He had loaded them with 78 grains of 630 instead of 785 IIRC, but the action did exactly as it was designed to do. Ruger offered to send him a new rifle & pay his doctor bill. He talked to a lawyer who wanted to sue Ruger and wrote them to that effect. I had kept one of the cartridges and called Ruger's legal dept and offered to testify for em. The lawyer dropped it when he heard that).0 -
In 25 years I have only seen an example of this first hand one time. Many years ago at a public range a fellow was firing an old sporterized 1903 which he received from his grandfather. Along with the rifle came a coffee can full of old ".30-06" ammo...green and awful looking...but that was not the problem. The firing line was hot and we were shooting when we suddenly heard shouts and screams from far down the firing line. This fellows 03 had blown out its magazine housing and split the stock in two pieces. The guy was in some pain and his fingers were burned. What had ended up happening was the classic 8mm Mauser cartridge inside a .30-06 chamber. The action held tight, although the pressures must have been well above a proof round, but the rifle was now junk. It turned out the coffe can held all sorts of mixed rifle ammunition and this guy had no idea what he was supposed to be shooting in his 03. He picked out a round that looked right, single loaded an 8mm round (only one round..."to be safe") and it was the wrong choice! Grandpa's 03 went to the trash heap.
Mark T. Christian0 -
That's an amazing (and scarily cautionary) tale, Mark---I myself own a nice refurbished (and non-sporterized) '03-type Springfield. But I have to say, I'm astonished someone could possibly jam an 8mm Mauser round in one---I've tried it myself! I gave a bag of .30-'06 to a friend of mine, and I sorted through it first. Much to my unease, I found an 8mm Mauser round in it, and double-checked all the cartridges before I gave it to him. Then, I decided to see what would happen if I'd missed any of the Mauser rounds, so I hauled out my Springfield and tried to chamber one. The result: I couldn't get that bolt to go forward enough to even ATTEMPT to turn the bolt-handle down and close the breech. Unless that guy really honked on that bolt-handle and smashed that 8mm round into that Springfield breech, I can't see how he could have done it without at least FEELING that something was wrong!
...Or is it possible that his Springfield was so worn by that time that the Mauser round could slip in?0 -
8/25/02 Ruger 77MKII 300WM Deer camp in Magdalena
fired 1 shot of "hunting loads" given to me by crusty old hunter-type that lived down the block (gave up hunting due to arthritis).
Nothing abnormal happened as far as recoil, sound, bullet placement; just a weird smell. Went to load another round and couldn't open bolt.
Noticed an itch on forearm-hair on fire, blood dripping down to elbow, mag cover stuck in wrist 1 1/2".
Case separated just past belt, melted/eroded almost all of mag spring and follower.
I'll use my own reloads from now on thank you very much!
If you know it all; you must have been listening.WEAR EAR PROTECTION!0 -
Excellent advice Gunnut. I NEVER shoot anyone elses reloads. No one covers your butt like you do ). That Ruger had tremendous pressures in it and that's what it's designed to do. Those big holes in the botton of the bolt and the design of the action let those gasses out the mag well. The case I mentioned above and youra may wel have had a blown barrel/receiver with a Remmington or Weatherby etc (with no place to vent that much pressure). That means more liklihood of serious injury to the shooter or bystanders.0 -
The barrel or action blowing is rare. I have seen for myself the 700 remington that blew the bolthead, completely of the bolt body, at my gunsmiths shop. A small tap from a rubber mallet, and the bolt opened. The ruger 77 is a better gas venting design, but no action explodes or hand grenades where another action contains the blast completely. If one explodes, the other just explodes slightly less, the tonnage of steel between the actions isn't that varied. If the differences were that pronounced, there would only be several makers in the market and all others would be out of business from inevitable lawsuits and bad publicity. the action/barrel threads would no doubt be stressed, and unuseable, but blowing them apart is catestrophic. Some vent better than others....none can hold more than about 80,000-90,000psi +/-. The weatherby is probably one of the strongest actions ever made, with it's 9 locking lugs, and biult primarily to handle some of the heaviest factory charges available to this day.
The hand grenade effect is an oversized bullet vs bore issue the large majority of the time. No action will hold that high of a PSI. definitely not in a 30 caliber or worse yet, a magnum loading. If you can at least get the bullet to travel the barrel, the gasses will be greatly reduced over the duration of the pressure curve. As the bullet travels, the compression area is increased, and the gasses can expand more readily, reducing pressures (albeit not as much as you need). The lodging of a projectile, doesn't creat a pressure curve, it creates a spike,......and the explosion is inevitable, as even the magazine well can't effectively vent enough gas pressure in a short enough time. Kind of like filling a balloon that has a pin hole in it, with an air compressor. It's still going to pop.
Your mileage may vary.
why chase the game when the bullet can get em from here?....
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