How do I headspace this rifle
- Thread starter Bandit06
- Start date
GEM
Senior Member
First you need it checked with headspace gages. Gages available from Brownells and others. See various YouTube videos or a gunsmith. If the heads pace is off then machining is required. Basic equipment required is a lathe to machine the barrel at the breach and a barrel vise to remove and install the barrel. Depending on the situation a chamber reamer may be needed. Note that this is a bare summary and each case is different requiring evaluation by an experienced tech.
BTW If the barrel, action and bolt are all an original set then it is highly likely that the headpace is ok. Even with a mismatched bolt most 98 actions will have proper headspace as those tolerances were held very close to spec by various makers. But always best to check for safety.
BTW If the barrel, action and bolt are all an original set then it is highly likely that the headpace is ok. Even with a mismatched bolt most 98 actions will have proper headspace as those tolerances were held very close to spec by various makers. But always best to check for safety.
O boy is this a bag of worms;
A quote from some of my old SRF stuff
Forster and Clymer gauges can be easily purchased in the US. I like special order Mason or CH4D gauges. Forster’s web site mentions that at some point in the 8mm Mauser history the shoulder on the cartridge/chamber of the rifles changed from 20 degrees to 19 degrees. The earliest record of the SAAMI specs being 19 degrees was in 1980 and that there is documentation of the 20 degree shoulder from 1938 to 1947. Consequently, they recommend that older guns in 8mm Mauser should be tested using their gauges meant for the older 20 degree shoulder. For most cartridges there is a .010/.011 inch difference between the minimum and maximum chamber specs.
There are 3 gauges GO NO GO Field (reject)
Go is the minimum chamber specs.
No-go is generally cut .003/.005 larger than minimum. This is what gunsmiths generally use to chamber a new barrel and not have it too "tight".
Field is the max chamber specifications
Headspace measurement is not an exact science it’s a measurement based on an arbitrary datum line on the shoulder of the case. The problem is there is are differences where gauge makers measure this datum line between the modern SAAMI and the original CIP Military chamberings. There are also minor differences in specifications between gauge manufacturers. For example, it has been observed that Clymer SAAMI, 30-06 gauges are cut closer to the original 30-06 specs. Foresters gauges are also SAAMI. But here are instances where a bolt will close on a Forster FIELD, but be OK with a Clymer gauge. So I always suggest using a different method to get an idea of the gap between the bolt face and back of the cartridge in a chamber.
8x57 Forester headspace gages measure
1.874 - GO
1.880 - NO-GO
1.884 - FIELD could be 1.888 for 8mm Mauser?
I know a Forester, Enfield .303 FIELD SAAMI measures .070, not a CIP of 074. So that is a difference of at least .004
Triebel in Germany are the only ones that use to make 8mm Mauser gauges that are supposedly military CIP specifications. I do not know the measurement of their FIELD gauge.
see https://www.triebel-guntools.de/en/chamber-gauges-for-rifle-calibers.html
There are different calibers? If it is an old 8mm 7x57 Mauser like a GEW 98, K98k, Turk 8mm, 98/22s or a Czech vz 24 there are two different 8mm Mauser gauges sold by Forster . Both are SAAMI and not military spec German gauges. So if you want to play it safe and check an old mauser as to the safe range you use a FIELD gauge. I do not even worry about a NO GO. If a Mauser chambers on a dummy round, it will pass a GO gauge. I am only concerned with a test that shows it's out of headspace and could be unsafe. You should have a military spec headspace gauge, you will never find a Mauser one on the cheep. Therefore, most use easily purchased Forster or Clymer gauges that are SAAMI spec. Now there are two gauges the 19 degree FIELD for newer mausers, and the 20 degree for older military mausers. If it is a k98, get the 20 degree Forster gauge. Clean the bolt and chamber, slip the gauge under the extractor and slide the bolt and lightly close it down on the gauge. NO FORCE . An ever so light touch. It should not close with a light touch. I do this at gun shows- no one is going to allow you to remove the extractor. If the bolt hangs about half way open/closed you are really good. If the bolt almost closes, but still does not close, it's still ok, but near the end of its headspace. If the bolt just falls easily closed and shuts down on the FIELD gauge, I leave it sit like a hot potato . HOWEVER, this Forster 20 degree gauge is SAAMI spec and the rifle many still be OK and pass on a military spec gauge. For me it's too close of a call, I do not need a Mauser at the end of its life. So I figure if it passes ok on a SAAMI FIELD gauge it's definitely OK with a tad of a safety factor in my favor. Just realize that rifle that just failed a SAAMI field gauge, may still be good to go toward the end of its life on a military spec gauge. If it is a deal, or something you want, you may want to buy it and take it home and use other methods I refer on SRF posts. You need a different FIELD gauge for each caliber you buy. 6.5 , 7 or 8 mm mausers. DO NOT use the 19 degree gauge unless its a modern hunting rifle in 8mm.
Other ways to measure. Do a headspace check without headspace gages to determine the gap. You only get a general idea. Really just so -so.
FIRST Primer Test method
Obtain an empty unfired cartridge, or pull the bullet and dump the powder, fire the primer, then remove the primer and save it. If you use new brass you must full length resized the new empty cartridge case. Measure the cartridges overall length with a set of vernier calipers and record it.
First,insert the spent, fired primer in the primer pocket. You just want to lightly set it in, not ram it down. Just start the spent primer level in the primer pocket. Seat it just enough that it doesn't fall out.
Second, slowly close down the bolt on the cartridge. It will start to push in the primer, partially seating the primer into the pocket. After the bolt is closed, open the bolt and remover the cartridge case.
Next, take the calipers and you want to remeasured the cartridge with the primer. You should see the primer slightly protruding from the rear of the case. It will not be fully seated. The height of the primer’s protrusion is the headspace gap between the bolt face and cartridge. See what you have as a reading and record the measurement of the cartridge. Be sure to measure over the primer to the other end of the case.
Final step, now it’s time to do some math. Subtract the first case measurement (Base to end without the primer in) from the second measurement (Base over primer to the end) and this will give you the GAP measurement in thousandths of an inch for any bolt action rifle. This is the headspace. Do this at least four times and get an average
reading. The headspace clearance between the rear of the case and the bolt face should be less than .012 to .014 for normal max headspace. Most likely around .010 /.011. If you get a measurement of .015-.025 that is not good.
Second Method: Poor Boy headspace:
The Poor boy Method of Headspaceing
Now you can use the Poor boys headspace test It only provides a general idea. You go to Hobby Lobby or Ace and buy some thin craft solder. Not the thick normal solder. This is the thin narrow stuff.
1) Clean the bolt, chamber, and barrel of the rifle. Keep the bolt assembled.
2) Obtain or make a Dummy round from an unfired, new factory ammunition case. Make sure it is a new cartridge and OAL is the same as the live ammo. Mark the tip and pull it, dump powder, and drill primer. Replace the bullet tip to the mark and measure OAL. Is it the same? Do not use a live round in the house. Or use a new live round at the range DANGER
3) Take the dummy cartridge and place it in the chamber
4) Point the rifle down with the open bolt to the rear
5) Take a length of craft solder and carefully place it over the back of the cartridge. It must lay across the entire cartridge back. It can be half moon shaped so it touches both ends of the cartridge.
6) Slowly close the bolt down onto the craft solder and the bolt face will smash flat the section of solder against the back of the cartridge case.
7) Slowly open the bolt in order to save and remove the flattened piece of craft solder. Measure the thin crushed down ends and see what the measurement of the crush is. Do not measure where the primer space is, just the nicely crushed ends that show the gap between the cartridge and the bolt face. Record the measurement.
8) Do this process three times with a new section of thin, craft solder and get an average of the headspace gap between the bolt and cartridge. Are your measurements around .011- .015 or less? You most likely are OK. You are within hand grenade range for a half as... sample attempt at headspace. If your measurements exceed .015 and are something like .025-.045 you best buy a real headspace gauge and do a correct headspace test on a FIELD gauge and see if the bolt closes on a REAL FIELD reject gauge.
Now this is a poor boys test, not really accurate, but it will give you a general, crude idea of where the rifle falls. Below .011/.012 you are good.
Not military spec gauges
If the bolt matches, I bet you are oK. If you want to spend some cash just get a cheep Forster 20 degree FIELD gauge ( not CIP). If the rifle passes on a Forster "Field gauge" its good to go- and then some. If it fails, then you may still have a rifle that passes on a military CIP Max gauge. Be sure the bolt and chamber are clean and slip the gauge under the extractor and see what you get. I only found missmatched beat Turk Gew98s and other old $49 Turk Mausers that failed and had a bolt close down. At $49 those were used as parts. All RC K98k and Mitchell mausers will have great headspace. Do not waste money testing them.
A quote from some of my old SRF stuff
Forster and Clymer gauges can be easily purchased in the US. I like special order Mason or CH4D gauges. Forster’s web site mentions that at some point in the 8mm Mauser history the shoulder on the cartridge/chamber of the rifles changed from 20 degrees to 19 degrees. The earliest record of the SAAMI specs being 19 degrees was in 1980 and that there is documentation of the 20 degree shoulder from 1938 to 1947. Consequently, they recommend that older guns in 8mm Mauser should be tested using their gauges meant for the older 20 degree shoulder. For most cartridges there is a .010/.011 inch difference between the minimum and maximum chamber specs.
There are 3 gauges GO NO GO Field (reject)
Go is the minimum chamber specs.
No-go is generally cut .003/.005 larger than minimum. This is what gunsmiths generally use to chamber a new barrel and not have it too "tight".
Field is the max chamber specifications
Headspace measurement is not an exact science it’s a measurement based on an arbitrary datum line on the shoulder of the case. The problem is there is are differences where gauge makers measure this datum line between the modern SAAMI and the original CIP Military chamberings. There are also minor differences in specifications between gauge manufacturers. For example, it has been observed that Clymer SAAMI, 30-06 gauges are cut closer to the original 30-06 specs. Foresters gauges are also SAAMI. But here are instances where a bolt will close on a Forster FIELD, but be OK with a Clymer gauge. So I always suggest using a different method to get an idea of the gap between the bolt face and back of the cartridge in a chamber.
8x57 Forester headspace gages measure
1.874 - GO
1.880 - NO-GO
1.884 - FIELD could be 1.888 for 8mm Mauser?
I know a Forester, Enfield .303 FIELD SAAMI measures .070, not a CIP of 074. So that is a difference of at least .004
Triebel in Germany are the only ones that use to make 8mm Mauser gauges that are supposedly military CIP specifications. I do not know the measurement of their FIELD gauge.
see https://www.triebel-guntools.de/en/chamber-gauges-for-rifle-calibers.html
There are different calibers? If it is an old 8mm 7x57 Mauser like a GEW 98, K98k, Turk 8mm, 98/22s or a Czech vz 24 there are two different 8mm Mauser gauges sold by Forster . Both are SAAMI and not military spec German gauges. So if you want to play it safe and check an old mauser as to the safe range you use a FIELD gauge. I do not even worry about a NO GO. If a Mauser chambers on a dummy round, it will pass a GO gauge. I am only concerned with a test that shows it's out of headspace and could be unsafe. You should have a military spec headspace gauge, you will never find a Mauser one on the cheep. Therefore, most use easily purchased Forster or Clymer gauges that are SAAMI spec. Now there are two gauges the 19 degree FIELD for newer mausers, and the 20 degree for older military mausers. If it is a k98, get the 20 degree Forster gauge. Clean the bolt and chamber, slip the gauge under the extractor and slide the bolt and lightly close it down on the gauge. NO FORCE . An ever so light touch. It should not close with a light touch. I do this at gun shows- no one is going to allow you to remove the extractor. If the bolt hangs about half way open/closed you are really good. If the bolt almost closes, but still does not close, it's still ok, but near the end of its headspace. If the bolt just falls easily closed and shuts down on the FIELD gauge, I leave it sit like a hot potato . HOWEVER, this Forster 20 degree gauge is SAAMI spec and the rifle many still be OK and pass on a military spec gauge. For me it's too close of a call, I do not need a Mauser at the end of its life. So I figure if it passes ok on a SAAMI FIELD gauge it's definitely OK with a tad of a safety factor in my favor. Just realize that rifle that just failed a SAAMI field gauge, may still be good to go toward the end of its life on a military spec gauge. If it is a deal, or something you want, you may want to buy it and take it home and use other methods I refer on SRF posts. You need a different FIELD gauge for each caliber you buy. 6.5 , 7 or 8 mm mausers. DO NOT use the 19 degree gauge unless its a modern hunting rifle in 8mm.
Other ways to measure. Do a headspace check without headspace gages to determine the gap. You only get a general idea. Really just so -so.
FIRST Primer Test method
Obtain an empty unfired cartridge, or pull the bullet and dump the powder, fire the primer, then remove the primer and save it. If you use new brass you must full length resized the new empty cartridge case. Measure the cartridges overall length with a set of vernier calipers and record it.
First,insert the spent, fired primer in the primer pocket. You just want to lightly set it in, not ram it down. Just start the spent primer level in the primer pocket. Seat it just enough that it doesn't fall out.
Second, slowly close down the bolt on the cartridge. It will start to push in the primer, partially seating the primer into the pocket. After the bolt is closed, open the bolt and remover the cartridge case.
Next, take the calipers and you want to remeasured the cartridge with the primer. You should see the primer slightly protruding from the rear of the case. It will not be fully seated. The height of the primer’s protrusion is the headspace gap between the bolt face and cartridge. See what you have as a reading and record the measurement of the cartridge. Be sure to measure over the primer to the other end of the case.
Final step, now it’s time to do some math. Subtract the first case measurement (Base to end without the primer in) from the second measurement (Base over primer to the end) and this will give you the GAP measurement in thousandths of an inch for any bolt action rifle. This is the headspace. Do this at least four times and get an average
reading. The headspace clearance between the rear of the case and the bolt face should be less than .012 to .014 for normal max headspace. Most likely around .010 /.011. If you get a measurement of .015-.025 that is not good.
Second Method: Poor Boy headspace:
The Poor boy Method of Headspaceing
Now you can use the Poor boys headspace test It only provides a general idea. You go to Hobby Lobby or Ace and buy some thin craft solder. Not the thick normal solder. This is the thin narrow stuff.
1) Clean the bolt, chamber, and barrel of the rifle. Keep the bolt assembled.
2) Obtain or make a Dummy round from an unfired, new factory ammunition case. Make sure it is a new cartridge and OAL is the same as the live ammo. Mark the tip and pull it, dump powder, and drill primer. Replace the bullet tip to the mark and measure OAL. Is it the same? Do not use a live round in the house. Or use a new live round at the range DANGER
3) Take the dummy cartridge and place it in the chamber
4) Point the rifle down with the open bolt to the rear
5) Take a length of craft solder and carefully place it over the back of the cartridge. It must lay across the entire cartridge back. It can be half moon shaped so it touches both ends of the cartridge.
6) Slowly close the bolt down onto the craft solder and the bolt face will smash flat the section of solder against the back of the cartridge case.
7) Slowly open the bolt in order to save and remove the flattened piece of craft solder. Measure the thin crushed down ends and see what the measurement of the crush is. Do not measure where the primer space is, just the nicely crushed ends that show the gap between the cartridge and the bolt face. Record the measurement.
8) Do this process three times with a new section of thin, craft solder and get an average of the headspace gap between the bolt and cartridge. Are your measurements around .011- .015 or less? You most likely are OK. You are within hand grenade range for a half as... sample attempt at headspace. If your measurements exceed .015 and are something like .025-.045 you best buy a real headspace gauge and do a correct headspace test on a FIELD gauge and see if the bolt closes on a REAL FIELD reject gauge.
Now this is a poor boys test, not really accurate, but it will give you a general, crude idea of where the rifle falls. Below .011/.012 you are good.
Not military spec gauges
If the bolt matches, I bet you are oK. If you want to spend some cash just get a cheep Forster 20 degree FIELD gauge ( not CIP). If the rifle passes on a Forster "Field gauge" its good to go- and then some. If it fails, then you may still have a rifle that passes on a military CIP Max gauge. Be sure the bolt and chamber are clean and slip the gauge under the extractor and see what you get. I only found missmatched beat Turk Gew98s and other old $49 Turk Mausers that failed and had a bolt close down. At $49 those were used as parts. All RC K98k and Mitchell mausers will have great headspace. Do not waste money testing them.
Attachments
Last edited:
Good to know, the barrel bolt and action are all original but the barrel is still not how it should be, might just get a new barrel, also in 8mm, because the outside of the barrel where bubba beat the front stock retaining ring piece thing off with a hammer scraped the snot out of the barrel