Can I get an idea of headspace by using factory 7.62 and 308 cartridges and measuring the space behind the right bolt lug? After stripping the bolt of the firing pin, ejector and extractor of course. If so, what would be a good figure? A couple of thou over 7.62?
M305 / M14 Can I check headspace with a cartridge?
- Thread starter Grizzlypeg
- Start date
The problem is that you have no idea what your starting point is - is the cartridge case minimum spec, maximum spec, or off-spec?
I believe that Hungry has a standing offer - send him some fired cases, and he will measure them and tell you exactly where you stand.
I believe that Hungry has a standing offer - send him some fired cases, and he will measure them and tell you exactly where you stand.
The measurement would tell you that for a specific cartridge, there is x thousandths of slop between the right lug and the locking abutment. Measure with 10 random cartridges, and average the measurement, and it will be a bit more accurate. I'm not sure what you would do with the measurement, though. It is all very well to use gauges to determine whether the rifle is within NATO or SAAMI tolerances, but how would you make use of the measurement obtained from the use of cartridges?
Good question. I know that some guys set their barrels on savage's using unprimed, sized brass. They put a thin tracing paper shim on the back of the cartridge and snug it up on that.
Ultimately you'd need to know what clearance there is on a properly headspaced rifle for comparison.
Ultimately you'd need to know what clearance there is on a properly headspaced rifle for comparison.
maple_leaf_eh
CGN Ultra frequent flyer
The headspace gauge looks like a solid steel cartridge case. It will be exact dimensions, whereas a cartridge is quite variable.
There is a material sold in auto supply stores called Plasti-gauge, that is like a crushable feeler gauge. One discussion on a Lee Enfield forum talked about using a sized empty cartridge case and small sections of this material against the bolt face. When you can't close the bolt, there is too much material. When you can close the bolt against resistence, measure how much material you've got.
It is however no substitute for a genuine headspace gauge used properly.
There is a material sold in auto supply stores called Plasti-gauge, that is like a crushable feeler gauge. One discussion on a Lee Enfield forum talked about using a sized empty cartridge case and small sections of this material against the bolt face. When you can't close the bolt, there is too much material. When you can close the bolt against resistence, measure how much material you've got.
It is however no substitute for a genuine headspace gauge used properly.
brownells sells the 308 go gauge for 20 somethin bucks..... then use the lazerus2000 method of cutting .001 thick auto feeler guages to stack behind the gauge.... keep adding them till you close up snug.... then measure the right hand lug gap. You can by the complete guage set from brownells for 199.00
they aren't gun parts so, there should be no restrictions on ordring.
they aren't gun parts so, there should be no restrictions on ordring.
In my clinic I'll have you take your barreled receiver out of the stock and remove the op rod spring.
Then allow the bolt and oprod to slide fwd and back without any spring tension.
Now let the bolt and op rod forward into battery (right lug engaged).
Now locate the scalloped are across the right hand lug on the top of the bolt and place yer thumb there.
Once you got yer thumb there, push the bolt forward until it stops travelling. Good, now under thumb pressure, let the bolt jockey rearward.
NOTICE the little bolt play or bolt slop I call it ? I showed this to you CGNutz at the Calgary clinic hosted at TSE(home of Redleg and TSEJr).
You will observe some bolt play of about 10 thou or so. Strangely enough, I use this technique (SWAG- Scientific Wild Ass Guess) to complement my Univ of Alberta degree in Science and now I can predict your headspace, fire the rifle 5 times and then mic your brass. Almost all of the time I am right (not always right according to my wife, but I am right with the M14 issues )
As a side observation, at the Calgary Clinic, I dropped in a new TRW bolt that another CGNutter was kind enough to bring alone.
NO Bolt SLOP !! ANYWHERE!! That's when I have experienced (and Skullboy and Lazerus2000) ZERO headspace variance from the SAAMI 1.630" GO gauge or chamber dimension. Match Chamber - Holy Batzhit, Batman
Hope this ever so Scientific (Hungry Welfare styles) method helps you out.
Do this test RFN (right now) and see for yerself. This is one of the exercises I like to show in my clinics.
How does one teach "feel" of bolt slop or hear the "Ping" test over the internet ? That's why you have to come to my clinics and learn first hand....
Then allow the bolt and oprod to slide fwd and back without any spring tension.
Now let the bolt and op rod forward into battery (right lug engaged).
Now locate the scalloped are across the right hand lug on the top of the bolt and place yer thumb there.
Once you got yer thumb there, push the bolt forward until it stops travelling. Good, now under thumb pressure, let the bolt jockey rearward.
NOTICE the little bolt play or bolt slop I call it ? I showed this to you CGNutz at the Calgary clinic hosted at TSE(home of Redleg and TSEJr).
You will observe some bolt play of about 10 thou or so. Strangely enough, I use this technique (SWAG- Scientific Wild Ass Guess) to complement my Univ of Alberta degree in Science and now I can predict your headspace, fire the rifle 5 times and then mic your brass. Almost all of the time I am right (not always right according to my wife, but I am right with the M14 issues )
As a side observation, at the Calgary Clinic, I dropped in a new TRW bolt that another CGNutter was kind enough to bring alone.
NO Bolt SLOP !! ANYWHERE!! That's when I have experienced (and Skullboy and Lazerus2000) ZERO headspace variance from the SAAMI 1.630" GO gauge or chamber dimension. Match Chamber - Holy Batzhit, Batman
Hope this ever so Scientific (Hungry Welfare styles) method helps you out.
Do this test RFN (right now) and see for yerself. This is one of the exercises I like to show in my clinics.
How does one teach "feel" of bolt slop or hear the "Ping" test over the internet ? That's why you have to come to my clinics and learn first hand....
Ishootguns
Regular
- Location
- Acton Ontario
GP you need a RCBS precision Mic in .308 Win.
Dave
Dave
I showed people how to use the RCBS Precision Mic at the Calgary Clinic in Nov, last month. They run about $ 60 or $ 70 at WhxleSxle Spurts in Calgary and they are specifically made for each caliber.
Is it worth spending that money ? For ME it is.... I shoot lots and lots of .308 Win handloads. Good to know. Even better for LCF (look cool factor) on the firing mound when you go around and show people how to mic their brass for headspace.
These are the kinds of tools that help you monitor what's going on inside your chamber. Really helpful if you shoot more than one boomstick in that caliber. So I bought another RCBS Precision Mic in .223 Rem for TWO other .223 boomsticks. Many of my friends send 5 pc batches of brass for me to measure and then email the sizes back to you.
This offer is open to anyone who reads this message...
Is it worth spending that money ? For ME it is.... I shoot lots and lots of .308 Win handloads. Good to know. Even better for LCF (look cool factor) on the firing mound when you go around and show people how to mic their brass for headspace.
These are the kinds of tools that help you monitor what's going on inside your chamber. Really helpful if you shoot more than one boomstick in that caliber. So I bought
another RCBS Precision Mic in .223 Rem for TWO other .223 boomsticks. Many of my friends send 5 pc batches of brass for me to measure and then email the sizes back to you.This offer is open to anyone who reads this message...
The RCBS guage is handy if you have a number of rifles the same caliber. As a quick test, chamber a round, gently, in which the primer has been only partly seated. If the primer stills ticks out a lot after the bolt has been fully closed, you got a headspace problem. If the primer is almost fully seated, the rifle is ight enough to shoot.
I had a local guy check the head space on my .303 and all he used was a couple of peices of black electrial tape cut 1cm x 1cm. I questioned it and he said the the tape is .003. Going his way on my .303, one peiceis ok, two is not. It seemed to work...
It seemed to work..."...Can I get an idea of headspace by using factory 7.62 and 308 cartridges..." No. Headspace is a manufacturing tolerance that allows different manufacturer's ammo to be used in any firearm. ONLY proper headspace guages will tell you if the rifle's headspace is within said tolerance. Headspace guages don't measure anything though. They only tell you if the headspace is within tolerance.
Cartridges DO NOT have headspace either.
"...all he used was a couple of peices of black electrial tape..." Find a smithy who actually knows what he's doing and has the proper guages. Bits of tape, brass shims and cartridges tell you nothing.
Cartridges DO NOT have headspace either.
"...all he used was a couple of peices of black electrial tape..." Find a smithy who actually knows what he's doing and has the proper guages. Bits of tape, brass shims and cartridges tell you nothing.
