Headspace
Please explain headspace. Safety concerns. There are so many reasonably priced 8mm Mausers on the market right now I would like to buy one or more. The problem is the one's I've looked at bolts and recievers numbers don't match. I know one should have rifle checked by a gunsmith before purchasing but this is not possible. Is this something I could check with a gauge. Also are the gauges for one caliber or adjustible for more than one caliber. Thanks in advance.
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I have an Ar-15 that i would like to switch the barrel on. When i remove the other barrel and put the other on will i have to have any headspace gauges seeing how they are the same brand barrels. Thanks 0 -
The "headspace" issue is highly overrated. In the Mausers, if headpace is inadequate, you cannot get a round in thge chamber! (Never happens). If it is very excessive, you will get weak strikes and occaisional misfires. Also the case will stretch, sometimes to the point of separation. The Mauser has more than adequIate shooter protection to prevent injury. If the headspace is slightly excessive (and most military rifles are deliberately designed and built to have more headspace than a commercial rifle, in order to function dirty) you will have SLIGHT lengthening of the case. If you are shooting surplus ammo, just discard the cases. If you are reloading, then neck size only, no problem.
I have been shooting all sorts of militaries for 50 years without regard to numerical match. I have NEVER experienced a safety problem
as long as the ammo matched the rifle!
Good luck. Have fun be careful!Morty0 -
The subject of headspace can be as simple or as complex as you wish. In laymans term it is the distance from the breech face to whatever part of the chamber which stops the foreward movement of the cartridge. Head space is important (though apparently not to everyone posting here) because if it is too great the cartridge will go to far into the chamber. This could casue the firing pin to be unable to make a solid hit on the primer, or the case may stretch so much when the round is fired that the case head can rip off and leak gas back toward the shooter. Modern rifles have a built in gas bleeding system to prevent the shooter being injured by this, but with the case head ripped off you now have a jammed rifle and you'd better have a broken case extractor handy. Without enough head space the cartridge may not even chamber or the bolt could be impossible to close.
All guns have head space and different cartridges head space differently depending on their design: Rimmed cartridges head space on the rim, most belted cases on the belt, and rimless cases like .30-06 head space on a particular area of the shoulder- often called the datum line. Head space will change over time but if you use factory loads it generally remains well within tolerences for the life of the firearm. If you shoot a lot of hot reloads you should be keeping your eye on the head space as wear will be greatly increased. Many surplus militray rifles were fired A LOT and could be worn to the point of the head space being out of adjustment.
There are gauges for checking head space. The two most useful (don't worry about the field reject gauge) are "Go" and "No Go". On the go gauge the bolt should close easily with no resistance. The bolt should not close easily on the no go gauge. If the bolt closes partially that is okay, but the gun is becoming worn and is nearing the head space limit- closure on no go does NOT indicate the firearm is worn out...but it is wearing. If the bolt slams closed easily on the no go gauge you are finished and should not shoot the firearm. Any closure on a field reject gauge indicates that the gun is totally worn beyond acceptable limits. If your rifle has developed excessive head space take it to a gun smith and see if he can set back the barrel and re cut the chamber. This is a very simplified over view of a very complex subject and I have left out quite a bit of technical jargon that would probably not interest you. I hope this helps.
Mark T. Christian0 -
Mark pretty much said it all so I can only emphasize what he said: quote:when the round is fired that the case head can rip off and leak gas back toward the shooter.
NRA ENdowment, CRPA Life, NRA ILA EVC, Past President NRA Members Council
Quod principi placuit legis habet vigorem. Semper Fidelis
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It's also important to keep "causing possible property damage, injury, or death" in mind, too. 0 -
If your case head seperates, and the ignition is released into the chamber, it will find it's way out the magazine well and trigger recess. Now let's look at it this way,.....50,000PSI, well over a thousand degrees, and your hand. HMMMMM
The mauser has a design that vents the gasses away from the shooters face when/if a seperation or incorrect caliber firing takes place, that is better than most. All that means is that you have less chance of having to remove the bolt from your face, but the gasses and brass particles are still going somehwere,.....and out the barrel is not an option. HEED THE ADVICE GIVEN. Mark Christian and Shootist 3006 have been around, and are giving you a heads-up, and I'm just agreeing with them. Mark has helped me in the purchase of a military rifle in the past,...and his advice and knowledge are SPOT ON!!!
why chase the game when the bullet can get em from here?....
Got Balistics?0 -
Yep, a head space guage is for one calibre only. It's a precision machined guage that is made to quickly check the head space for a specific calibre. It doesn't measure anything. As far as safety goes, gas coming back is the least of the problem. It's entirely possible for the entire bolt to come back and embed itself in your head. 0 -
Wisco:
I add my voice to those above suggesting that you should be concerned (very concerned) about headspace issues, if you value your health.
Excessive headspace can cause case failure resulting in white hot high pressure gas escaping into the receiver, and where it will escape the action is anyone's guess. Catastrophic failure of the bolt or magazine and stock, or the escape of these gases to the rear is not something you want to be around (as in right next to your head) when it occurs.
If you are trying to fly economy class, you will still need to spend a little dough to protect yourself. Get yourself a properly sized cartridge and a field reject guage for the rifle you want to buy. If the cartidge fits, headspace is at least adequate. But if the bolt closes on the field reject gauge, headspace is excessive and the rifle should not be fired without repair. Frankly, I would use a "no go" gauge rather than the field reject gauge; there are plenty of these rifles out there, so why not find one closer to optimum? These steps are probably all you will be able to do before purchasing. (I assume you are familiar enough with rifles generally to examine the rifle for other problems.)
Prior to test firing I would use cerro-safe to make a chamber casting and a leade casting. Measure and examine these for other problems (chamber deformities, excessive leade, etc.) If you want to shortcut here, you can test fire. Personally, I go to a safe place, set the rifle in an old tire, tie a string to the trigger, and fire from a protected position. Examine the cartridge case and rifle. If no problems are apparent, repeat a couple of more times until it seems likely that all is well.
Be careful. Shooting is supposed to be a pastime, why take unecessary risks?
redcedars0 -
quote:quote:
when the round is fired that the case head can rip off and leak gas back toward the shooter.
Yep, and it comes around the bolt and right into your eye, and it will blind you. Had the opportunity to meet a man it happen to in western Pa. Totally blind in the right eye. Had to learn to shoot left handed.
Measure twice, cut once.
Empty the clip!0
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