AR Sponsor
Posted: 5/2/2014 12:53:56 PM EDT
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Guys I took my finished build to a local gun smith that builds quit a few AR's to have him check the head spacing. The guy even has build classes on building AR's in his shop and is respected around here for being pretty sharp. Anyway, I was told by him that checking the HS on an AR is a mute point because you can't adjust it anyway. All the GS did was drop a live round into the barrel while it was off the gun and just kind of eyeballed the setting of the round and said "looks good" and reinstalled the barrel.
The barrel is a new 1:9 twist from ar15sports and the bolt & receiver is the latest round of the Mil surplus parts kits. I'm torn weather I should revisit a different gunsmith or take this one's word, so I thought I'd do a little poking around here for advise. I would like to get the crowds view on, if head spacing the AR is needed or not? How do you correct HS if you do find a problem? Just thoughts in general??? |
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Guys I took my finished build to a local gun smith that builds quit a few AR's to have him check the head spacing. The guy even has build classes on building AR's in his shop and is respected around here for being pretty sharp. Anyway, I was told by him that checking the HS on an AR is a mute point because you can adjust it anyway. All the GS did was drop a live round into the barrel while it was off the gun and just kind of eyeballed the setting of the round and said "looks good" and reinstalled the barrel. The barrel is a new 1:9 twist from ar15sports and the bolt & receiver is the latest round of the Mil surplus parts kits. I'm torn weather I should revisit a different gunsmith or take this one's word, so I thought I'd do a little poking around here for advise. I would like to get the crowds view on, if head spacing the AR is needed or not? How do you correct HS if you do find a problem? Just thoughts in general??? I'm guessing you meant to type "because you can't adjust it anyway." I'd say the "sharp" gunsmith is pretty "dull". You could build 1000 AR's with new parts and never check the headspace and never have a problem, then the 1001'st would give you problems. If headspace were excessive or short, no you can't adjust it, but you could find out what was out of spec and change/replace that. All I can say is he must be damned talented to eyeball headspace, lol. |
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He's right in the fact that there is (for all practical purposes) no way to adjust the headspace. However, I would disagree this negates the requirement to check the headspace. The tech manual calls for a headspace check, and just because you can't adjust the headspace, does not automatically make it good.
With that said, if the barrel and bolt are in good shape and manufactured to spec, the headspace check will pass. If the barrel/bolt are worn greatly, the check may fail. I find it hard to believe that anyone has eyeballs calibrated good enough to check headspace just by looking. That is fascinating! John Thomas |
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When I was a 45B we did the annual inspections for our weapons, and other units weapons.
All we ever used was a field gauge. It was all we had. Coded out some NG Infantry unit's M60's for headspace once. They were kinda pissed at us for that. 
I have seen some commercial barrel/bolt combos that failed a no-go, but not a field. |
YEP...... That's what I meant to type "can't" 
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I'm guessing you meant to type "because you can't adjust it anyway." I'd say the "sharp" gunsmith is pretty "dull". You could build 1000 AR's with new parts and never check the headspace and never have a problem, then the 1001'st would give you problems. If headspace were excessive or short, no you can't adjust it, but you could find out what was out of spec and change/replace that. All I can say is he must be damned talented to eyeball headspace, lol. Quoted:
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Guys I took my finished build to a local gun smith that builds quit a few AR's to have him check the head spacing. The guy even has build classes on building AR's in his shop and is respected around here for being pretty sharp. Anyway, I was told by him that checking the HS on an AR is a mute point because you can adjust it anyway. All the GS did was drop a live round into the barrel while it was off the gun and just kind of eyeballed the setting of the round and said "looks good" and reinstalled the barrel. The barrel is a new 1:9 twist from ar15sports and the bolt & receiver is the latest round of the Mil surplus parts kits. I'm torn weather I should revisit a different gunsmith or take this one's word, so I thought I'd do a little poking around here for advise. I would like to get the crowds view on, if head spacing the AR is needed or not? How do you correct HS if you do find a problem? Just thoughts in general??? I'm guessing you meant to type "because you can't adjust it anyway." I'd say the "sharp" gunsmith is pretty "dull". You could build 1000 AR's with new parts and never check the headspace and never have a problem, then the 1001'st would give you problems. If headspace were excessive or short, no you can't adjust it, but you could find out what was out of spec and change/replace that. All I can say is he must be damned talented to eyeball headspace, lol. |
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I find it hard to believe that anyone has eyeballs calibrated good enough to check headspace just by looking. That is fascinating! He got the sizzle with no steak
That's a dog and pony show to get you to drop it and just go shoot. Most people would take his word and be done with it. As said before it _should_ be in spec, should be checked, and if you want to force the issue make the GS use the gauges in front you (and read on how to use them before you go!). |
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You can inspect with properly sized round, bolt and carrier and barrel installed. Don't know how to do it without A BCG. Properly sized round is basically a headspace guage. There are many tell tale signs from out of spec chambers but one probably needs to inspect a whole lot of brass to be able to do so. I've trimmed so much brass over the years I can actually look at it and tell if it needs a trim 95 plus % of the time. That's 95 plus % of the time not 100%. Brass will still go in my case length guage regardless and head space guage's will go in barrel.
Problem is deterniming if properly sized round used is actually properly sized and for this one would need a case length / sizing guage. Lot more factory ammo is out of spec than most would think and it still shoots fine. It's definately not a point worth arguing about. I use HS guages but have never seen one out of spec that I assembled with the parts I used in a whole bunch. Have seen them in pics and magazine articles. More than likely to sell guages. Could easily be more prevellant in machine gun setting where rifles are seeing a lot more rounds than I can afford under a variety of conditions I can't repeat. You can take a little off the bolt face if necessary but most all would simply swap another bolt. With chrome chamber you can't adjust chamber that I know of. I believe in VN during early stages before chrome chamber it wasn't unheard of to ream the chamber with a drill but GI's were getting killed and rifles were malfunctioning. It's a nice / intelligent move to have a concern and guage mfgs can't sell guages if they aren't needed. Being that it's a weapon that see's enormous pressures in barrel and chamber and on bolt face when fired next to face it's something that is carefully monitored in the mfg stage and rarely passes through quality control from a quality mfg. Usually stems from extension being improperly installed or as stated bolt face worn out of spec (highly used). Weapon will still function fine more than likely. Some USGI swap them to keep allocations high for just in case. Kinda like destroying ammo with no training involved so they can simply order some more. |
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Couple different standards so a couple different answers, think standards are SAaMII and ANSI but I didn't stay at the Holiday Inn last night or bother to look up. As stated if only purchasing one guage the field guage is the one to buy. Have seen rifles, not mine, that fail a no go guage and shoot fine and have for thousands of rounds. I prefer bolt not to close on field guage, no go guage and to close on the go guage.
Again I'm not gonna piss over it but to properly do it the bolt ejector and extractor should be removed from bolt for accurate measurement. Many do it differently with no failures and again chances of having an out of spec chamber / bolt are very slim. |
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I prefer bolt not to close on field guage, no go guage and to close on the go guage. Just asking because I don't know........ When you say you "prefer not to close on the field guage" is that the actual test of the function in the field as well? I may pick one up just to have as the price of it is not to bad just for the single gauge.....If that's enough to get me by? |
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When you say you "prefer not to close on the field guage" is that the actual test of the function in the field as well?
That is correct. If bolt closes on field guage it fails. If not going to build a bunch of AR platform rifles might spend the coins elsewhere IMO. Some get anal and worry about this stuff and some simply shoot their rifle builds and enjoy them. Even with HS checked and GTG I still get nervous when I pull the trigger the first time, always have and always will. Decent build is usually the sum of it's parts although I've bought some pretty big coins items, advertised and supported by this guy and that guy and actually they were simply overpriced junk IMO and other less spendy lower tier items would eat their lunch all day long. It's todays advertisement strategy. Hard to advertise something for top tier coins as junk and sell it. |
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Headspace on an AR barrel is set when the barrel extension is installed. Your 'smith is right; there's no feasible way to adjust. So you're saying because there is no feasible way to adjust it that.........what...........you shouldn't check it? Adjust?...no Correct?...........yes |
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Headspace also factors in a barrel's endurance. The detail specifications MIL-DTL-70599B for the M4, and MIL-DTL-32209 for the M16A4 states headspace for a new barrel shall be checked after proof firing a M197 High Pressure Test Round.
The minimum headspace shall not be less than 1.4646" (Go Gage) when measured from the bolt face to the .330 datum line, and the maximum headspace shall not be greater than 1.4706" (No-Go Gage). The "endurance headspace measurement" (what the DTL calls it) for weapons fired with 30 round magazines after 50 cycles or 6,000 rounds, headspace shall not be more than .0028" greater than the initial measurement; and shall not exceed .0024" over the maximum headspace, or 1.4730" (Field Gage) when measured from the bolt face to the .330 datum line. Now the SAAMI Specification for 223 Remington the minimum headspace is 1.4636" (Go Gage), 1.4666" (No-Go Gage), and the chamber's maximum headspace before deemed unsafe is 1.4736" (Colt II Field Gage). Using a round to check headspace is not going to tell much, for cartridges within the SAAMI specification vary between 1.4596" to 1.4666" from the cartridge's rim to the .330 datum line. The three gages I would keep on hand would be a 1.4636" (Go Gage), a 1.4666" (No-Go Gage), and a 1.4736" (Colt II Field Gage). If you're starting with a new barrel, and do not own any gages; you only need to start with the first two gages, and later on picking up a Colt II Field to do a yearly headspace check as called for in TM 9-1005-319-23&P. |
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You can inspect with properly sized round, bolt and carrier and barrel installed. Don't know how to do it without A BCG. Properly sized round is basically a headspace guage. There are many tell tale signs from out of spec chambers but one probably needs to inspect a whole lot of brass to be able to do so. I've trimmed so much brass over the years I can actually look at it and tell if it needs a trim 95 plus % of the time. That's 95 plus % of the time not 100%. Brass will still go in my case length guage regardless and head space guage's will go in barrel. Problem is deterniming if properly sized round used is actually properly sized and for this one would need a case length / sizing guage. Lot more factory ammo is out of spec than most would think and it still shoots fine. It's definately not a point worth arguing about. I use HS guages but have never seen one out of spec that I assembled with the parts I used in a whole bunch. Have seen them in pics and magazine articles. More than likely to sell guages. Could easily be more prevellant in machine gun setting where rifles are seeing a lot more rounds than I can afford under a variety of conditions I can't repeat. You can take a little off the bolt face if necessary but most all would simply swap another bolt. With chrome chamber you can't adjust chamber that I know of. I believe in VN during early stages before chrome chamber it wasn't unheard of to ream the chamber with a drill but GI's were getting killed and rifles were malfunctioning. It's a nice / intelligent move to have a concern and guage mfgs can't sell guages if they aren't needed. Being that it's a weapon that see's enormous pressures in barrel and chamber and on bolt face when fired next to face it's something that is carefully monitored in the mfg stage and rarely passes through quality control from a quality mfg. Usually stems from extension being improperly installed or as stated bolt face worn out of spec (highly used). Weapon will still function fine more than likely. Some USGI swap them to keep allocations high for just in case. Kinda like destroying ammo with no training involved so they can simply order some more. HUH? I have never seen a reason to do this nor heard of this being done. What I am saying is, excessive headspace is a possible condition, (not common) but I have never heard of an AR-15 or M16 that wouldn't chamber a round. Please explain further. |
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First make sure you have an absolutely clean chamber and locking lug recesses. Then remove ejector from bolt, so pressure from ejector does not skew the results.
Use finger pressure only, with bolt out of bolt carrier, and do not force things. ABSOLUTELY do not check with bolt still in bolt carrier and with any possibility of dropping the BCG on the gage like when chambering a round, unless you wish to possibly ruin your gage. Bolt closes on "GO" gage = Good. Bolt DOES NOT close on "NO GO" gage = Good (and no need to check with FIELD gage if it doesn't close). Bolt closes on "NO GO" gage = Not so good, check with "FIELD" gage. Bolt closes on "FIELD" gage = Bad. If bolt closes on NO GO but will not close on FIELD, reduced case life can be expected, if you're a reloader and care about such things. If you are building a precision rifle and/or using new pieces/parts, you should not accept condition where bolt closes on NO GO but will not close on FIELD. A good explanation can be found here, that pretty well backs up what most everybody has already said: Insert gage here |
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HUH? I have never seen a reason to do this nor heard of this being done. What I am saying is, excessive headspace is a possible condition, (not common) but I have never heard of an AR-15 or M16 that wouldn't chamber a round. Please explain further.
Morg, Probably because most just drop the bolt and it closes. As stated none of my bolt's or builds does the bolt close except on a go guage. Possibly luck of the draw. Have seen bolts that close on a no go guage just none of mine. I've never had personal experience with removing material from bolt face or lugs but have been told this is what had been done when one purchases a matched competition bolt and barrel combo by BM rep and others. Maybe I misunderstood what I was told by vendors rep who sell the comp bolt / barrel combo and possibly typical salesman BS to justify the extra $50. Doubt seriously CS rep actually builds the custom combos. Would make more sense that they do what most do and simply swap bolts if a problem exists when guaging to get one that checks correctly. Granted bolts are all supposed to be the same spec. I've never actually measured bolts for comparrison but have a few Colt's stashed to check. Not like we have options when making a bolt purchase. I have seen performance combos that have different numbers on baggie the bolt comes in with what appear to be measurements. I said bolt face but could also be lug face depending on circumstance. I've also had barrel machinist tell me they do this. Possibly more BS to justify an extra $50. I've never personally had a headspace issue as stated or seen one bad enough to effect function. As Andouille explained or what I gathered, was it will effect life of brass, more important for competition shooters and reloaders who basically blue print a load for speciffic needs / economics. Does appear like guy writing SGN articles runs into a HS issue nearly every time he builds an AR and then shows Brownells part number for guage purchase. I have seen tight chambers at case mouth where inserting brass will marr case or actually mark the case mouth with Sharpie / dykem or such and see marking is removed from mouth when brass is extracted and chamber got an additional ream. These were custom pieces. I've also bought and measured M-193 Nato stamped ammo which was over spec right out the gate crimped and factory fresh exceeding 1.76 case max by my calipers but usually still 2.25 or real close COL so it fits the mag. Popular with import ammo also. Many time's this is why it's available on civillian market IMO and not on some military base. Same as plenty of Federal stamped .223 case length is 1.73. Don't think short brass is the issue but probably can be if pressure gets too high on shorter COL.. Ammo has always fired fine but not what I'd call to spec. Few are gonna measure factory fresh ammo. There also is a difference in .223, 5.56, wylde etc. Usually leade is longer and not shorter when measured with comparator but leade isn't what I call chamber size but distance to lands or grooves. It appears I have been doing HS wrong according to post above as I strip my bolt then install with carrier and guage and ease forward to make sure bolt closes. Field guage = no close. No go = no close and go guage = close. Been doing it this way for a long time. Step 1, step 2, step3. GTG and go shoot. Never had a problem with function and all my brass fired from my rifles/ carbines never exceeds 1.76 telling me my chambers aren't wasted yet or still in spec. I trim to 1.750 regardless and after a couple firings it's usually still 1.756-1.758 after firing. I still trim to 1.750 for supposedly consistency. Anal? Brass length seems to be consistent per gun also when measuring the fired lot. Same gun = same brass length within .001-2. I do believe as brass flows forward in case and wears out this may change but I rotate so much ammo none of my brass has exceeded 3 firings to date. (K's of ammo) Thanks members AR-4C and Andouille for increasing my knowledge on this subject. |
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It appears I have been doing HS wrong according to post above as I strip my bolt then install with carrier and guage and ease forward to make sure bolt closes. Uh, I thinks maybe my corners are getting cut full round again. Generally I headspace new bolt to new barrel before installing in receiver, so if there is a problem no time was wasted putting together and taking apart.........so fingers work with that method, but would be PITA for checking headspace if the barrel was already torqued into the receiver. Your way is how I'd do it if the barrel was already installed. Up too late and not thinking, sorry. I would repeat and clarify my caution to not check headspace with a fully assembled rifle, for fear of dropping the bolt on a chambered gage. Separate the upper and lower assemblies, strip the bolt and use Cdenmark's method under those circumstances. |
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I just measured 6 MPC Colt bolts. 3- NOS I removed from package and 3- used $25ea purchases from Tar Heel Ordnance. Overall length from tail to lug face was 2.795 on new bolts rotating gently and 2.794 on used missing a litlle parkerizing. Granted these are pretty nice used bolts. Not for sale!
I then measured from lug face to bolt face and all measure 0.125 inch. rotating them trying to stay consistent but I could easily have not been perfectly centered / squared using depth guage on caliper but good enough for me as reading was basically the same. Rotating tail measurement 0.251-0.252 on all. Used are showing wear and fluxuation from 0.251-.0.252 but new was 0.251 constant. I didn't apply a lot of pressure but tried to stay constant. Appears the used have moved metal .001 or finish as dimension actually increased in areas. Even if calipers are off +/- .001 they appear consistent. I also measured band as this shows a little wear on used bolts and new was 0.529 and used were 0.528. Tells me parkerizing is rather thin in reality. I don't think I learned much except that the bolts I purchased on surplus market were nearly identical in dimension to those removed from Colt package. None of these have been headspaced but never having a HS issue I'm gonna assume they are fine and simply have kept for spares as I have 9 - 5.56 AR's and 1 - 7.62x39 which I actually don't have a spare bolt for but strickly hunting carbine and has approximately 100 rds down the pipe and bolt is still as new. Almost tells me surplus bolts were trashed due to lack of lubrication as gas rings were worn and I had replaced them when initially purchased. Almost leads me to believe that a milspec bolt has to see some serious use without lube to actually wear much. I run my AR's very wet generally unless I leave my CLP at home but usually keep a large can in my shooting bag. For walk-a-bout I lube prior and rarely even shoot in the woods. Keep mostly for my protection. 200 lb bear, rabid dog or such could really mess one up rather quickly. Don't think this adds much to headspace discussion but I had to know once I thought about it. Makes me wonder why the surplus bolts were actually trashed / replaced / possibly stolen and sold? For giggles I measured a P marked narrow band chrome Colt in excellent condition. Amazingly it measure 2.803 end to end, .0125 from face to lug, tail was 0.252 and band was 0.529 so these things haven't changed much in 50 years. |
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Separate the upper and lower assemblies This! Andouille, I have your name just can't remember without checking e-mail. Only problem with my method I've really had is removing headspace guage without extractor on bolt and I use a simple hook to remove after check. Can be a small pita but beats throwing it across the room. I've never headspaced or even thought about headspacing a barrel before I installed it but that's exactly how the factory does it I'm pretty sure. I've always been more concerned how it is after being assembled and check before shooting. As stated I've never had one out of my guage spec to date. I have also assembled without a guage and fired but used the properly sized brass and looked for scratching, wear etc on brass. Worked fine. If I see abnormalities on brass that weren't there before installing I then break out the scope for a peak. Usually machining debris I missed on cleaning. I'm getting old and new bulbs don't put out much light in my den / workshop / dungeon. About the lowest tier barrel I've ever bought was DSA and it was fine also. I also only use Colt, FN or Young bolts. I did sell my 6K plus test BCG back with Obamo II for the coins but it had never not functioned and a couple of those test uppers did fire brass above 1.76 max telling me throat had wear. Sold as is! I definately check everything I purchase on EE and auction settings before considering taking a shot. |
| Cdenmark - FWIW the chamber in the stock XM16E1 seemed excessively tight when we were test firing it, but soon loosened up. The ejection pattern started at 3:00 and ended up at about 4:30 consistently. The ejection wasn't really consistent for the first 50 rnds or so IIRC. One question - why would you strip the bolt when USGI gauges and most commercial are relieved for the extractor? I mean, you throw a USGI gage in it and you know. I do see the value in owning a go and no-go if you are reaming a chamber, or checking it for duty involving blue ribbons, but other than that I just don't get it. |
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Morg,
FWIW the chamber in the stock XM16E1 seemed excessively tight when we were test firing it, but soon loosened up.I Think I remember reading after a few hang ups armorers took the drill to non chrome chambered barrels and put a little clearance in them. They are FA and were probably exposed to a lot more heat than what I'm used to, mud and crud, no cleaning kits, etc. although also I find it hard to believe military had guns and no gun oil but if people are shooting at you one may not have the time. Know more than one ex-vet from WWII or Korea who wizzed on their weapons / MG's to cool them down. For question, I simply don't own a USGI guage. Directions said strip bolt and I'm anal! I measure way too much. I actually like messing with this stuff so it's no big deal. Can still assemble, check etc in an hour or so which isn't long when parts gathering is considered for a retro. Really never had a FTF or FTF in lots of rds in mine. I did stick one re-load that I evidently loaded too long for bullet profile. Was a Speer SP like 50ish and I'd set COL too long. Caught it before I squeezed the trigger and then hand pulled 39 just like it when I got back home. That blew! Had to really tug on the CH to dislodge so possibly one FTF but I'm pretty sure it would have gone bang even in the lands as it was. Lesson for me: Read and stick to mfg load data and don't re-invent the wheel, lesson learned and no foul. Been looking for USGI guage but $1 short, day late. USGI tools are kinda scarce and pricey when found. Kinda like your chrome XM16E1 BCG. Buddy has a complete USGI M-16 armorers kit he got from someone that has tools in it I couldn't imagine using or how to use and I'm a tool guy. Very nice kit, looks expensive for the tax payer. Mine is a commercial set from Brownells via reading SGN and recommendation years ago. Think it's a Forster or such but would actually have to look. I've never paid much attention to where brass went. Just that it went. All mine throw it a litle differently but in the same spot per gun. Again I look more for consistency. It does appear the ambient temp has a little effect but could be amount of oil, brand of brass, chamber size ,brass sizing, etc. Lots of variables on throwing brass besides bolt. |
| I on occasion will rebarrel from a blank, and thus am reaming the chamber. This requires the use of headspace gauges. Once you do that it just seems like the thing to do.........check headspace on all your builds. Like I said in my first reply, a guy could put together a thousand rifles and never have a problem, then the 1001st would. Most all of us have thousands of dollars in AR's, so what's a 50 dollar gauge? |
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I on occasion will rebarrel from a blank, and thus am reaming the chamber. This requires the use of headspace gauges.
This is what the mfg's do also. Guess the potential problem lies when the lunch whistle blows as with most anything mfg'd in USA besides Mondays and Fridays lemmons. I'm sure a lot of this is automated today. Robots, robotics, etc. I wonder if they can forget to do something? Weren't any robots around or retro! Danger, Will Robinson! |
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I would always check headspace, especially with the high volume of parts being produced these days and by many different suppliers, all trying to keep up with backlogs from the high demand. The last BCG I received from BCM was from a different supplier than those purchased in the past, so they are sourcing from various contractors to keep up. When you start mixing and matching bolts and barrels from various sources, you will get lots that will headspace different.
There is a variance out there, for instance, the Spike's bolts tend to headspace on the loose side, while DD bolts on the tight side. BCM, CMT and Colt bolts are very close but still on the tight side if used with a Wylde chamber. I've found that most bolt lugs and the bolt face fall within a range of .002" variance from one brand of bolt to another. But, there are exceptions, of all the bolts I have the variance range is .003" from the Spike's to the CMT. Note that the .223 GO and NOGO range is only a .003" window, so mix and match and there's a chance you could fail either the GO or NOGO. A barrel turned by CLE is headspaced very tight and will likely fail the GO gauge unless you order a matched bolt. .223 Wylde chambers are usually headspaced tighter than 5.56 NATO by .001". An AR-15 can experience various issues if it fails the GO and any new build needs to fall in the SAAMI .223 GO and NOGO range for the best reliability and safety with both .223 and 5.56 ammo. This is the same for both .223 Wylde and 5.56 NATO chambers if you plan to fire both .223 and 5.56 ammo in them. I have used the Forster .223 gauges for 20 years and always had best luck if the bolt closes EASY on the GO but doesn't come anywhere near closing on the .223 NOGO. That's where I get best accuracy and reliability with correct chamber pressure and can achieve higher round counts before the accuracy drops off due to wear and increased headspace. Now, if it closes tight on the GO or fails to close on the GO then you will have increased chamber pressure and an increased chance of pierced primers or popping primers. Fired brass will more likely show signs of high pressure, even in factory rounds. You may also have an increased chance of extraction problems with carbine length gas systems. I've also had slam fires in .223 Wylde chambers with tighter headspace combined with extra power recoil springs. Hornady factory 75gr match with the silver primers will pierce regularly in rifles with tight headspace, as will reloads with WSR primers. You can still chamber a round even if it fails to close on a GO gauge, so you can't tell without the gauge. For best reliability with the widest range of ammo, the bolt should NOT close TIGHT on the GO gauge. It should close EASY with VERY LIGHT finger pressure and do this with the extractor removed so you can tell what you are doing. You should not put any more pressure than what is just needed to compress the ejector spring. If it closes tight, that's the same as a fail when dealing with an AR-15, it really needs just a tiny bit of headspace past a GO. If it fails the .223 NOGO you will have a decrease in chamber pressure but increased case stretch, which is not best for those who reload. With more case stretch you have an increased chance of case head separation. You also need to be more careful, since .223 brass is much softer than Mil brass and will stretch more. I would not fire any hot reloads in any rifle that fails a .223 NOGO. Accuracy will start to fall off once you fail the .223 NOGO. If you want the best accuracy, the bolt should not close on a .223 NOGO. The .223 GO and 5.56 NATO GO are the same size. The .223 NOGO is .003" longer than the GO. The 5.56 NATO NOGO is about the exact same size as a .223 Field, so I find no reason to purchase the 5.56 NOGO. The 5.56 NATO NOGO is intended for use in repair and inspection to grade rifles headspace for combat. Pass the NOGO test and it is still ready to go into combat, but fail the NOGO and it stays in the states for training purposes only. The 5.56 NATO NOGO is not a good spec for building a new rifle as you don’t want a new barrel and bolt combo to come anywhere near closing on a 5.56 NATO NOGO gauge, especially if you plan to fire any .223 or reloads. The .223 field Gauge is of limited use on a new build, it is a reject gauge that tells when it is no longer safe to fire .223 ammo. The Colt field or NATO Field gauge is a reject gauge that tells when it is no longer safe to fire 5.56 NATO spec ammo. |
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Separate the upper and lower assemblies This! Andouille, I have your name just can't remember without checking e-mail. Only problem with my method I've really had is removing headspace guage without extractor on bolt and I use a simple hook to remove after check. Can be a small pita but beats throwing it across the room. I've never headspaced or even thought about headspacing a barrel before I installed it but that's exactly how the factory does it I'm pretty sure. I've always been more concerned how it is after being assembled and check before shooting. As stated I've never had one out of my guage spec to date. I have also assembled without a guage and fired but used the properly sized brass and looked for scratching, wear etc on brass. Worked fine. If I see abnormalities on brass that weren't there before installing I then break out the scope for a peak. Usually machining debris I missed on cleaning. I'm getting old and new bulbs don't put out much light in my den / workshop / dungeon. About the lowest tier barrel I've ever bought was DSA and it was fine also. I also only use Colt, FN or Young bolts. I did sell my 6K plus test BCG back with Obamo II for the coins but it had never not functioned and a couple of those test uppers did fire brass above 1.76 max telling me throat had wear. Sold as is! I definately check everything I purchase on EE and auction settings before considering taking a shot. You buy a new barrel from White Oak or Compass Lake (among others) and you can have them include a new bolt already headspaced to the barrel. It's cheap insurance. There was a circular firing squad of a group hissy fit here a few weeks/months ago about the need to check headspace and the relative danger or lack thereof of not checking it. I think the argument either ran out of steam or ended in a draw, or perhaps the smart kids just walked away from it, hoping they would never share a range with the delusional. I would only say that you can bet your sweet bippy that all the reputable manufacturers check headspace, and that there must be a reason for it. Two reasons, actually: fingers and eyeballs. There are several tens of thousands of pounds per square inch of very hot gas in very close proximity to the shooters snout each time a round is fired. People ignore stuff like this at their peril. 999 out of a thousand may be perfectly fine. Ah, but the one! That's the one that makes life very interesting! |
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Several years ago I picked up two USGI field gauges from Bill Ricca, one for myself and one for Olgunner. I don't use it often, but it was $35 well-spent
Probably close to what I spent a few years back. I also missed the throat erosion guages. There are several tens of thousands of pounds per square inch of very hot gas in very close proximity to the shooters snout each time a round is fired. People ignore stuff like this at their peril. 999 out of a thousand may be perfectly fine. Had a buddy missing a whole finger, a piece and an eyeball from basic training blow up and I'm guessing that M-16 was actually headspaced. Kept him out of VN and in a powder / explosive mafg facility. Still had to suck when every 6 year old asked what happened to his fingers even 30 years later. Guns really aren't toys and command a lot more respect than many give them. I was raised hunting, by real outdoorsmen, even being a suburb kid and I've never even pointed a gun at anything I wasn't planning on sending away from here, eating or a target shooting with exception of possibly a blank wall zeroing with no one around. Every time I walk into my LGS I'm surprised at all the people buying guns pointing them this way and that including the employees. I sometimes think to myself that the idiot making the purchase really needs the piece crammed where the sun doesn't shine. Oh, it's not loaded! Dad tells a true story of coming back from a hunt as a kid. His neighbor leaned his loaded shotgun against a tree after the hunt and his 4 year old somehow got the gun and blew his dad's head off not knowing what he had actually done. Bet that's been one tough life. Whole lot more to it than simply checking headspace. I met the guy recently at an auction and my dad is now 86. |
| I'm a lefty shooter.....you can bet your butt I know the headspace in my semi and auto rifles that eject right beside my face. They all get checked with a go and a no-go gauge regularly. I've never had one close on a no-go gauge, but have changed out a couple bolts and barrels when the case shoulder starts needing a good bit of push while resizing my spent casings. Brass inspection and resizing is just another benefit of reloading that many people never consider until they've been doing it long enough to notice when their brass just isn't right. |
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