Head space gauge
Printed From: Enfield-Rifles.com
Category: Enfields
Forum Name: Enfield Gunsmithing
Forum Description: Submit any how-to's or other gunsmithing suggestions here.
URL: http://www.enfield-rifles.com/forum_posts.asp?TID=8594
Printed Date: March 26 2026 at 8:52pm
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Topic: Head space gauge
Posted By: AbitNutz
Subject: Head space gauge
Date Posted: October 23 2017 at 12:31pm
| Are there any go-no-go gauges that are not SAAMI spec? I would really appreciate a set of gauges that are military dimensions. I have an expensive set of Forster gauges that are pretty much useless. I'm thinking of trying a field gauge but I suspect that may not work out either. |
Replies:
Posted By: Zed
Date Posted: October 24 2017 at 4:03am
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http://www.okiegauges.com/" rel="nofollow - http://www.okiegauges.com/ I have a full set of these for 303. They work well and not too expensive. Worthwhile if you have more than one rifle or considering buying more! ------------- It's nice to be important, but it's more important to be nice! |
Posted By: AbitNutz
Date Posted: October 24 2017 at 5:18am
| I have seen those but they seem totally alien to what I'm used to. How are they to use? Can you give me a rundown of your technique? |
Posted By: Shamu
Date Posted: October 24 2017 at 5:32am
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I have the same set. They work fine on rimmed cases because only the rim matters for headspace. My technique is: Wip oil from gauge. Remove magazine. Open Bolt. Point muzzle vertical. Place gauge on bolt face. Make sure cut fits extractor. Slowly close bolt with just one finger. STOP the moment you feel resistance. Open bolt. Remove gauge. Re oil. Close bolt. Ease springs. ------------- Don't shoot till you see the whites of their thighs. (Unofficial motto of the Royal Air Force) |
Posted By: AbitNutz
Date Posted: October 24 2017 at 5:52am
| So the difference in resistance between the go and no go gauges is it difficult to feel? |
Posted By: Bear43
Date Posted: October 24 2017 at 7:26am
| Get the Okie gauges, you will love them. They are so easy to use and are mil-spec. I highly recommend them. |
Posted By: Shamu
Date Posted: October 24 2017 at 9:19am
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There are 3 gauges in the set, one of which I doubt you'll ever use unless you're re-barreling. "Headspace gauges generally come in 3 sizes:
GO <----> NO-GO < ----> FIELD (One dimple) <> (Two dimples) <> (Three dimples) GO = 0.064"<------> NO-GO = 0.067" <> FIELD = 0.074".
GO:
measures the minimum acceptable headspace. This size is most often
used when re-barreling or re-chambering a firearm. The action should close on this gauge. It should NOT fully close on the other 2. NO-GO: This gauge is used to check for excessive headspace. If a firearm closes on the NO-GO gauge it is an indication that the weapon MAY not be safe to fire. Reloading ammunition for a firearm that fails NO-GO can result in unsafe loads due in part to the expended brass being elongated as a result of not being firmly chambered. Most military surplus firearms that pass NO-GO (the bolt will not fully close on the gauge) are considered safe to fire with surplus ammunition, or with modem loads not intended for reloading. FIELD: A firearm failing the NO-GO spec can be tested on the slightly more forgiving FIELD gauge. Military chamber specifications are generally looser than commercial firearms, giving them a bit of tolerance for adverse conditions such as dirty chambers, weather extremes, etc. A firearm passing FIELD spec (not closing fully on the gauge) is generally considered safe to fire the ammunition it was designed to fire, i.e. military surplus ammunition of the designated caliber." You're not feeling for resistance, just contact. Its reduced because of the camming action as the bolt is closed so just that very first touch is what you want. In reality you can probably get by with just the "0.074" "FIELD" gauge for most things as that was the only standard the British ever used. In practice I bought the set of 3 & I use the "NO GO" first. If the action fails the "NO GO" by closing fully & double check with the "FIELD" ------------- Don't shoot till you see the whites of their thighs. (Unofficial motto of the Royal Air Force) |
Posted By: AbitNutz
Date Posted: October 24 2017 at 10:23am
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They're far and away cheaper than the traditional SAAMI gauges I'm familiar with so, like you, I ordered the set. We'll see if I'm smart enough to make them work. I really appreciate the help.
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Posted By: Canuck
Date Posted: October 24 2017 at 6:14pm
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Great tools. I have two sets. One stays on my work bench the other comes with me to gun shows. Keep them well oiled, however, otherwise you might experience minute rust that could possibly throw off your measurement. This company who supplies these also supplies a striker depth of engagement (firing pin) gauge. This is a MUST tool in any LE owner's tool box IMHO. I know a person could use a depth gauge measurement using a caliper but....these gauges are just so neat. One thing I have found while using these gauges is that the gauge itself can slip loose after checking the head space upon disengagement and retraction of the bolt, so I use a magnetic tipped rod to extract the gauge. This helps with those 'oops' moments looking on the shop floor for the fallen gauge. ------------- Castles made of sand slip into the sea.....eventually |
Posted By: AbitNutz
Date Posted: October 24 2017 at 9:04pm
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I have an Enfield NO4 mk1 that is in really pretty good shape. Out of curiosity, I decided to check the headspace. The bolt will close even on my Forster SAAMI field gauge. Normally I would come unglued at this but I suspect it may be fine. I have come to the conclusion that these gauges when applied to Enfield rifles, are just about useless. I've yet to fire this rifle but intend to do so and see what the brass looks like afterward.
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Posted By: Shamu
Date Posted: October 25 2017 at 5:46am
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Failing SAAMI but passing MOD WOPS is pretty normal. ------------- Don't shoot till you see the whites of their thighs. (Unofficial motto of the Royal Air Force) |
Posted By: Bear43
Date Posted: October 25 2017 at 6:06am
| The Forster field gauge measures .070" as opposed to the military spec of .074". That's quite a difference so failing the SAAMI and passing the other is very common. |
Posted By: Link
Date Posted: January 24 2018 at 2:58am
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I had ordered an Okie field gauge. I received a refund notifying me Todd had passed away and my order could not be filled. Does any body have a spare Okie field gauge they would sell? Also, can someone tell me the OD of the Okie gauge? I have some .074 SS washers but turning them down will be horrible without proper tools. But I have time to try. Thanks
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Posted By: Canuck
Date Posted: January 25 2018 at 8:45am
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That's sad Todd passed away. I did not know of this until now. ------------- Castles made of sand slip into the sea.....eventually |
Posted By: Shamu
Date Posted: January 25 2018 at 10:41am
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That's sad he'd done great work for ever. I have a set, but they're not for sale. The OD measures: 0.53515" for the 1-dot GO = 0.064" 0.5350" for the 2-dot NO-GO = 0.067" 0.5350" for the 23-dot FIELD = 0.074" Measured across the sides so the cut for the extractor doesn't factor in. ------------- Don't shoot till you see the whites of their thighs. (Unofficial motto of the Royal Air Force) |
Posted By: Link
Date Posted: January 25 2018 at 11:42am
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Thanks Shamu. That's what I was wanting to know. BTW, I emailed Forster about making .074" field gauges and the techs are all at the Gun Show. Lady that wrote back said she would mention it to them. Also I email the Firewerks guys who also make the washer type gauges for Mosins. I haven't heard back. |
Posted By: Macd
Date Posted: January 27 2018 at 4:58pm
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I trust no one will take offense to me adding a few words that will be old news to the experienced members. Many times new shooters read these forums and this is for their benefit. Headspace is often a misunderstood concept. Brownells has a really good technical article on the subject (Google it) and the proper use of headspace gauges just as Shamu has explained above. Passing a field gauge is fine for most unfired brass but you increase your chance of case separation with even the second firing as the brass has likely been subject to excessive stretch on the first firing. The LE is already reputed to be hard on brass. Military chambers were designed to accept cartridges with generous manufacturing tolerances and in varying conditions of cleanliness. As long as the round fired and the empty case extracted the resultant condition of the fired case was unimportant. Neck sizing, annealing necks and avoiding high pressure loads can help prevent premature case failure. You can also measure rim thickness of cases and choose only those with the thickest rims. The minimum rebate in the chamber for the rim is .064" but you will find brass with rims that are well under this thickness. Fortunately correcting a headspace issue may be quite simple in the LE just by swapping out to a longer bolthead. If you are at the longest bolthead already then a barrel setback and re-chambering is needed. You will read about "home remedies" like putting an o-ring or other spacer ahead of the rim to effectively increase rim thickness or soldering a thin washer onto the bolt head. I have no experience with these "fixes" but it sounds like using pantyhose to replace a fan belt. It may work but I would avoid unconventional solutions. Will excessive headspace lead to a kaboom or other catastrophic failure? Not in my experience. It will lead to case separation, venting of gases and require removing the remaining part of the case from the chamber. It is also hard on the bolt and locking lugs/receiver channels. A prudent rifleman will remove the bolt and inspect the barrel to confirm it is clear. Safe shooting. |
Posted By: Shamu
Date Posted: January 28 2018 at 3:08pm
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Macd makes some good points, but even more is relevant. Rimless cases headspace totally differently from rimmed ones & it causes some confusion when the two are intermingled. Generous chambers can happen even with tight headspace & vice-versa so its important to understand how they both inter-relate. There's a .PDF I posted years back on headspacing for reloaders & the early part is pretty helpful on them, even if you don't reload. Let me see if I can find it. There were 2 versions a pre-photobucket crash (with all the images lost) & a post disaster one with them. I think (hope) this is correct version. http://www.enfield-rifles.com/uploads/3/smoking_cases.pdf" rel="nofollow - uploads/3/smoking_cases.pdf Yup, this is it. ------------- Don't shoot till you see the whites of their thighs. (Unofficial motto of the Royal Air Force) |
Posted By: Macd
Date Posted: January 28 2018 at 3:52pm
Excellent paper Shamu. Since this is a LE rifle forum we won't get into handgun cases unless someone really wants to  . Weatherby and other belted cases are another story too. |
Posted By: Link
Date Posted: January 29 2018 at 3:31am
| Very good! |
Posted By: Honkytonk
Date Posted: February 05 2018 at 6:03am
| I have a friend that is an awesome machinist. He is set to retire soon so I'd like to abuse him. I know a bit about headspace measurements. But do not have gauges as a gun store in town has some. If I brought my machinist friend an empty fresh resized 303 brass, could he duplicate that with a solid aluminum (he had access to slot of different materials) dummy and add .074 or Field measurement on to the rim? It sounds simple (for him) I must be missing something. I wouldn't think the ejector would be an issue, but again, looking for some sage advice. Thanks. |
Posted By: Link
Date Posted: February 05 2018 at 7:17am
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Try looking at Okie's headspace gauges. Since the .303 Brit is a rimmed cartridge they made the "coin" type gauge. Look at these: http://www.okiegauges.com/sales.html" rel="nofollow - http://www.okiegauges.com/sales.html You'll see they have a cutout for the ejector. Here's the info Shamu provided back on page 1. The OD measures: 0.53515" for the 1-dot GO = 0.064" 0.5350" for the 2-dot NO-GO = 0.067" 0.5350" for the 23-dot FIELD = 0.074" Measured across the sides so the cut for the extractor doesn't factor in. Put your friend to work.
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Posted By: Honkytonk
Date Posted: February 05 2018 at 7:32am
| Will do! Thanks! |
Posted By: Macd
Date Posted: February 05 2018 at 7:34am
Would look like this Forster gauge. Read use here. https://www.forsterproducts.com/pdf/instructions/Headspace_Gage_Instructions.pdf  |
Honkytonk wrote:Posted By: Honkytonk
Date Posted: February 05 2018 at 8:33am
| Yes! That's what I had in mind! Any opinions as to it or the discs work better? The same? Thanks! |
Posted By: Shamu
Date Posted: February 05 2018 at 9:02am
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I prefer the discs. Frankliy the problems of twisting sliding & so on a plug type gauge is something I prefer to avoid. Lets face it with a rimmed case all you need is the rim, nothing else counts. ------------- Don't shoot till you see the whites of their thighs. (Unofficial motto of the Royal Air Force) |
Posted By: Honkytonk
Date Posted: February 05 2018 at 10:00am
| I believe I will go with the discs. Thanks! |
Posted By: Link
Date Posted: February 05 2018 at 11:01am
| Seems like the disc would also be easier. I look forward to seeing what he can do. |
Posted By: Shamu
Date Posted: February 05 2018 at 1:36pm
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Basically yes. Get a rod of the diameter needed, run a key-way down one side, drill a center-bored hole & part off to length. ------------- Don't shoot till you see the whites of their thighs. (Unofficial motto of the Royal Air Force) |
Posted By: Link
Date Posted: March 19 2018 at 2:01am
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Good mornin', Just wondering if Honkytonk's machinist friend has considered this endeavor?
|
Posted By: Ranch Dog
Date Posted: March 19 2018 at 4:14am
| I would be interested in purchasing a set of "Okie" style discs as well. I wish I would have bought a set. |
Posted By: Shamu
Date Posted: March 19 2018 at 4:42am
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Its a shame but Okie was a one man band & he's passed on now. There's a definite niche market for these now so its time for HONKYTONK's buddy to jump in with a precise quality product. ------------- Don't shoot till you see the whites of their thighs. (Unofficial motto of the Royal Air Force) |
Posted By: Honkytonk
Date Posted: March 19 2018 at 4:56am
| I haven't talked to my machinist buddy for a while. The plant where I used to work at has had several unfortunate mechanical outages this year, so buddies workload is substantial. He has the design, but I suspect it'll be a while before I see the product. |
Posted By: Goosic
Date Posted: March 19 2018 at 6:46am
| In reading all these posts,I started thinking about one thing, bolt head size,and not the obvious #0,#1,#2,and #3 size,I mean the actual size of the bolt head between the same size numbered head,and then between the other three. The rifle I just built has a #2 bolt head,the Forester .070" Field gauge won't close on it. I measured the bolt head and it reads .0631. For s&#ts and giggles I measured all my spares. I have four #1's, two #3's,and three #2's. Three of the #1 measured .631,just like the #2 in my rifle however,one of those #1 boltheads read at .0632". Guess what I did. One of the #3's measured at .0637",and one of the #2's measured at .0636. The main thing here is that I have a rifle that passed the field gauge test with two different boltheads sizes and the shorter #1 is actually.001" longer then the #2. Use the head space gauges accordingly but take into careful consideration the actual wear on the bolt head face itself. |
Posted By: Shamu
Date Posted: March 19 2018 at 7:31am
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As long as they clock at less than 15° overturn that's great. There is a guy who has done a lot of research into head number Vs bolt length & you've confirmed his results. ------------- Don't shoot till you see the whites of their thighs. (Unofficial motto of the Royal Air Force) |
Posted By: Goosic
Date Posted: March 19 2018 at 8:11am
| None of mine clock any more then 12°. I went one more step in this endeavor of mine. I have three spare No4 bolts,the shortest one measured in at 5.525" and the longest one at 5.530". I'm looking at this from a functionality perspective too,so bear with me on this. If you are building an Enfield rifle for whatever reasons and you have discovered that you have a headspace issue even after you have installed the dreaded #3 bolt head. Go back,and if you have a couple of spare bolts,or bolt heads, gauge them,make sure they're measuring out to the standard size,and if not,check if you have one that is a couple of thousands of an inch longer,maybe an unissued one. Check the fit and functionality along with the headspace. You might discover that the issue was with a very worn bolt or bolthead,or both... |
Posted By: Goosic
Date Posted: March 19 2018 at 8:28am
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Think of it like this. Everytime,that you pull,or squeeze the trigger on that Enfield,that tiny .303 British hammer/case,beats the crud out of that bolt face,smashes that against the bolt,and then all that pressure is put onto the locking lugs. After awhile those items will get shortened in length. The face of the chamber wear comes from excessive chambering and rechambering of cartridges that wear out the area were the rim of the cartridge sits. Look at the bottom of the barrel were the bullet hits it after the feed ramp. If it's real bad, a barrel replacement will be necessary but,if it still has retained it's flat edge, check the bolt and bolt head. |
Posted By: Zed
Date Posted: March 19 2018 at 11:49am
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I replaced the bolt on my SMLE to get the headspace better. It was at the field limit. The new one has to be sufficiently long enough to be stoned to fit. It is essential that you have equal load on the lugs. It is a delicate operation to stone it to fit and not remove too much material; so as to retain the extra length. You've got 5 thou to play with and you may need to stone 2 or 3 of that to fit. So the actual improvement may only be 2 thou depending on how lucky you are. ------------- It's nice to be important, but it's more important to be nice! |
Posted By: Shamu
Date Posted: March 19 2018 at 12:24pm
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That's also the reason for the max 15° over-clock! Its so the forces will be transmitted to the bolt face by the shoulder on the bolt & the rear face of the head, not the threads! ------------- Don't shoot till you see the whites of their thighs. (Unofficial motto of the Royal Air Force) |
Posted By: Ranch Dog
Date Posted: March 21 2018 at 2:03pm
A buddy of mine, Al Nelson, who owns http://noebulletmolds.com/NV/index.php?osCsid=25t3cm0034s41tgffa133ofce1" rel="nofollow - NOE Bullet Moulds , called me today to visit. He has done a number of projects that I have suggested so he is going to look into these headspace coins. I sent Al the dimensions of the 303 British "coins" and if anybody has the same for the other cartridges offered, please post them.
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Posted By: Canuck
Date Posted: March 21 2018 at 2:12pm
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That's great, Ranch Dog! Please keep us posted. ------------- Castles made of sand slip into the sea.....eventually |
Posted By: Shamu
Date Posted: March 22 2018 at 5:11am
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The coin style for the .303 British also work for the mosin Nagant 7.62X54R round ------------- Don't shoot till you see the whites of their thighs. (Unofficial motto of the Royal Air Force) |
Posted By: GreySaber
Date Posted: October 27 2018 at 4:04am
| Bump. Does anyone have a source for military spec gauges? |
Posted By: englishman_ca
Date Posted: November 14 2018 at 11:31am
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My 0.074 FIELD gauge was made for me by a machinist on his lathe. It is accurate within less than 0.0005 inch which is well good enough for me. Top hat shaped, made from silver steel, it is heat treated and hardened. Easy peasy for somebody with a decent metal lathe and accurate vernier calipers that knows how to use them. The chap that was making the Okie disc ones passed away, so they are no longer in production. So if you do see a set for sale, grab em! There are ex-military head space guages that pop up on auction sites from time to time, but they are Lee Enfield collectables in themselves and can fetch silly prices.
------------- . . Look to your front, mark your target when it comes! |
Posted By: Shamu
Date Posted: November 14 2018 at 1:12pm
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Thisa should be the same as M-N & L-E are the same specs, just double check its really 0.074" https://www.amazon.com/Mosin-Nagant-Headspace-Gauge-Firewerks/dp/B0088AEBDG" rel="nofollow - https://www.amazon.com/Mosin-Nagant-Headspace-Gauge-Firewerks/dp/B0088AEBDG ------------- Don't shoot till you see the whites of their thighs. (Unofficial motto of the Royal Air Force) |