Nashmack
Member
IIRC, you can make a headspace guage out of a fired case and some masking tape. Does anyone know how to do this, or how many layres of masking tape I would have to add to the case head on a .308 case to make a 7.62 NATO gauge?
Masking tape headspace guage?
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Bwana John
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I always thought that it was a UN-fired case with masking tape on the base?. 
Nashmack
Member
I dont know, that's why I was asking
It's very ball-park, there's lots of variables to consider. Various actions have different closing pressures/leverage, and can crush the masking tape different amounts. Masking tape also isn't exactly a precision product either...
Then there's the variations in ammunition manufacture, not a lot of ammunition will mike as consistently as a well machined gauge set would.
That being said, tape headspace can give you a rough idea if a firearm is shootable or not.
Generaly, the "masking tape method" is an unfired round, (be careful, or remove firing pin etc.) 1 masking tape disk on the case head and the action closes is "GO", 2 masking tape disks on the case-head and the action closes is "FIELD", and 3 masking tape disks on the case head, and the action closes is "NO-GO"…
The real bummer though is that if you close on two tape disks, all you've really earned yourself is more checking. The amount of play in the "FIELD" category with the tape layers is too much to be sure. You don't know exactly where you stand until you try some real gauges.
My rule of thumb is that unless I can only close the action on "GO", or no tape at all, I need to do a proper check with gauges or a gunsmith.
Then there's the variations in ammunition manufacture, not a lot of ammunition will mike as consistently as a well machined gauge set would.
That being said, tape headspace can give you a rough idea if a firearm is shootable or not.
Generaly, the "masking tape method" is an unfired round, (be careful, or remove firing pin etc.) 1 masking tape disk on the case head and the action closes is "GO", 2 masking tape disks on the case-head and the action closes is "FIELD", and 3 masking tape disks on the case head, and the action closes is "NO-GO"…
The real bummer though is that if you close on two tape disks, all you've really earned yourself is more checking. The amount of play in the "FIELD" category with the tape layers is too much to be sure. You don't know exactly where you stand until you try some real gauges.
My rule of thumb is that unless I can only close the action on "GO", or no tape at all, I need to do a proper check with gauges or a gunsmith.
That's how I was taught!
I've done this many times. My drill is to use a case that has been resized in the dies I intend to use as a Go, and add one piece of tape (good masking tape will usually be .004" thick. VERIFY THICKNESS!!!) for a No-Go. That will leave you with a nice tight headspace.
The only problem I've ever encountered is factory rounds that won't chamber. It's very rare, and you want to gauge everything before using factory fodder anyway. This can be done with Plasti-Guage, a product available at most auto supply stores. You squeeze the bolt shut on the round w/P-G on the back, peel off the P-G and measure the thickness with calipers.
Hpoe this is helpful.
I've done this many times. My drill is to use a case that has been resized in the dies I intend to use as a Go, and add one piece of tape (good masking tape will usually be .004" thick. VERIFY THICKNESS!!!) for a No-Go. That will leave you with a nice tight headspace.
The only problem I've ever encountered is factory rounds that won't chamber. It's very rare, and you want to gauge everything before using factory fodder anyway. This can be done with Plasti-Guage, a product available at most auto supply stores. You squeeze the bolt shut on the round w/P-G on the back, peel off the P-G and measure the thickness with calipers.
Hpoe this is helpful.
Nashmack
Member
Thanks AJ and Will, I just checked headspace using the loaded round/masking tape combo and it passed. I also went down to the shop and ordered a set of actual gauges to be sure
I think that's just a tad bit off. No-go means it is safe to use, but will damage the brass and may cause rupturing. The largest of the three, field-reject, means it's unsafe to fire at all. In general, there is no point in using a field gauge, since an action that closes on the no-go gauge is probably unsafe to fire with commercially produced ammo. If you're headspacing all the MGs on the Western front to see which ones can be salvaged, the field gauge might be useful. For those of us with easy access to replacement parts and fewer encounters with divisions of German infantry, no-go is as big as it need be.
Some brass shim stock is a lot better way. It will not compress like paper.
The biggest issue is that the brass case itself is so soft it can deform and give a false conclusion when a steel gauge would be very difficult to close on (and can damage the gauge and gun if forced).
Real gauges are not that expensive.
The biggest issue is that the brass case itself is so soft it can deform and give a false conclusion when a steel gauge would be very difficult to close on (and can damage the gauge and gun if forced).
Real gauges are not that expensive.
JNewell
Member
Not tossing barbs at anyone with this, but for the sake of THR, it probably should be said that whether or not the masking tape method is a reasonable field expedient, the only way to make industry standard (and reliably safe) headspace measurements is with the right gauges.
Nashmack
Member
Like I said, I have a set on order. I used the masking tape as a field expedient.
silverlance
Member
imho
if i owned a range, especially if i owned one in take-all-your-evil-guns-away-and-leave-you-with-septugenarian-milsurps california, i'd have a full set of every no-go, go, and field gauge available. if that would be too expensive, i'd have a full set of no-go gauges at least.
then i'd rent them out along with a liability waiver to milsurp bunnies like me for, say, free for members, $10 for non-members.
i wish burro canyon had em.
if i owned a range, especially if i owned one in take-all-your-evil-guns-away-and-leave-you-with-septugenarian-milsurps california, i'd have a full set of every no-go, go, and field gauge available. if that would be too expensive, i'd have a full set of no-go gauges at least.
then i'd rent them out along with a liability waiver to milsurp bunnies like me for, say, free for members, $10 for non-members.
i wish burro canyon had em.
Jim Watson
Member
What is the urgency of headspace measurements?
Are you building a rifle?
Are you building a rifle?
Nashmack
Member
Jim Watson, My rifle is an FR7. It was originally an 1893/1916 Spanish Mauser in 7mm that was rebarreled to 7.62. The purpose of headspacing it before firing it with full power ammunition is to verify that it is in fact in the proper range, thereby preventing case head ruptures or bolt failures. For an explanation why this is important check www.surplusrifle.com and click on the link for the 1916 civil guard mauser.
Jim Watson
Member
Seems like a sensible move considering that those rifles were converted to a heavier caliber than they were originally made for and that many people will be shooting them with hotter ammuntion than even the conversion was for.
I am of the school of thought that those Spanish Mauser conversions were meant for 7.62x51 CETME ammo, which is a considerably lighter load than NATO or .308.
Do you plan to download, reload, or use reduced load factory ammunition as described in other articles on that site?
I think there is unnecessary attention paid to headspace on surplus rifles which are to be shot with factory or arsenal ammunition in their original caliber, but you have something entirely different here.
P.S. Do you know how to use a headspace gauge? It is not just a matter of dropping it in the chamber and closing the bolt as though on a cartridge.
I am of the school of thought that those Spanish Mauser conversions were meant for 7.62x51 CETME ammo, which is a considerably lighter load than NATO or .308.
Do you plan to download, reload, or use reduced load factory ammunition as described in other articles on that site?
I think there is unnecessary attention paid to headspace on surplus rifles which are to be shot with factory or arsenal ammunition in their original caliber, but you have something entirely different here.
P.S. Do you know how to use a headspace gauge? It is not just a matter of dropping it in the chamber and closing the bolt as though on a cartridge.
Nashmack
Member
I have a general idea of how to use the gauge, and I'll be checking it for the first time under the supervision of a smith.
The field manual for these guns state that they're made for use with 7,62 NATO, but that's an endless debate as far as the spanish mausers are concerned. I personally like the Spaniards, I find them to be of high quality and most of the 1916s I've examined have had beautiful stocks on them.
The field manual for these guns state that they're made for use with 7,62 NATO, but that's an endless debate as far as the spanish mausers are concerned. I personally like the Spaniards, I find them to be of high quality and most of the 1916s I've examined have had beautiful stocks on them.
Never thought of using plastigauge.....
that way you know what your headspace is............I used the tape process last night on a new Enfield I received and the bolt would only close about 3/4 of the way with one layer of tape. Bolt is mismatched too.......lucky I guess.....chris3
that way you know what your headspace is............I used the tape process last night on a new Enfield I received and the bolt would only close about 3/4 of the way with one layer of tape. Bolt is mismatched too.......lucky I guess.....chris3
JNewell
Member
One of the problems with the tape method is that it depends on the dimensions of the case you're sticking it to, which is not necessarily SAAMI-spec.
In addition to headspace, as Jim mentions, military chambers have other potential dimensional issues, one of which is chamber diameter (headspace measures only length). Excess diameter can result in case head separations if the case head is weaker than the original military brass spec'd for the chamber. In other words, you can have case failures even if the headspace is correct and the brass is new.
In addition to headspace, as Jim mentions, military chambers have other potential dimensional issues, one of which is chamber diameter (headspace measures only length). Excess diameter can result in case head separations if the case head is weaker than the original military brass spec'd for the chamber. In other words, you can have case failures even if the headspace is correct and the brass is new.
Nashmack
Member
As it's a Spanish mauser chambered for 7.62 NATO, I dont plan on firing any commercial loads through it.
I had my 'smith space it last night, closed on GO but didn't close on NO GO. I haven't fired it with full power NATO rounds yet, only loaded down frangibles. What would the brass look like if the chamber was out of spec?
I had my 'smith space it last night, closed on GO but didn't close on NO GO. I haven't fired it with full power NATO rounds yet, only loaded down frangibles. What would the brass look like if the chamber was out of spec?
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