View Full Version : Headspacing new rifle that I built
Long time lurker first time posting
Lets start off with what I have. I built a rifle with a DD lightweight barrel with a DD bcg. built on top of a spikes lower and upper. I went to a lgs store to see if they had a headspace gauge or even check my rifle. The response I got was "if built milspec everything should be fine". Now reading on this forum I really don't feel comfortable just firing because I built milspec. Now I am forced to by a gauge I am going to use only once. I guess this is more of rant than a tech question. Is there a online store I can get a headspace gauge that anyone would recommend. thanks for your help
You're probably OK but if it makes you feel better rent a set of gauges. http://www.4-dproducts.com/pdf/4d%20Price%20List_1012.pdf
I got mine from Brownells. Picked up the 5.56 set along with a set of 308s. I'm not sure where they rank as quality but they worked for me. I bought my set for my AR308 build, I was more worried about it than a 5.56 rifle. I just saw they had them for a 5.56 too so I picked that set up while I was at it.
If you were close to me you could swing by and use them. I tried shipping a tool once on a forum to help a guy out, after 2 years I finally got it back...I had given up on it and already replaced it by then. That's the last time I loaned something out to someone I couldn't see face to face.
Thanks I'll check them out for the rental.
I got mine from Brownells. Picked up the 5.56 set along with a set of 308s. I'm not sure where they rank as quality but they worked for me. I bought my set for my AR308 build, I was more worried about it than a 5.56 rifle. I just saw they had them for a 5.56 too so I picked that set up while I was at it.
If you were close to me you could swing by and use them. I tried shipping a tool once on a forum to help a guy out, after 2 years I finally got it back...I had given up on it and already replaced it by then. That's the last time I loaned something out to someone I couldn't see face to face.
I'll have to look up on brownells. I don't blame on loaning out tools as well. been burnt a few times also.
Auto-X Fil
01-06-16, 19:13
Midway and Brownell's both have affordable gauges. Just buy the no-go to check for excessive headspace. If a loaded round chambers, that's your "go" indication.
But, almost nobody headspace-checks ARs. I swap BCGs around all the time. Especially with a quality BCG and barrel from the same manufacturer, I wouldn't even consider doing it.
I've built several AR15s only using quality components (BCM, Noveske, or Rainier barrels, BCM BCGs). I've never headspaced one.
"Mil spec" covers a lot of muddy ground and doesn't necessarily equate to "quality".
elephantrider
01-06-16, 23:10
You really don't need a set of gauges, just the GO gauge should suffice. If checking brand new parts, your headspace should only be a few thousands over the GO/minimum. Check to make sure that the GO fits fine and then you can then check to see approximately how much over the GO you are by adding a thin piece of paper, or tape, to the base of the gauge and re-checking. Most paper is 0.001" thick and painters tape about ~0.003". You can check these with a caliper assuming you have one. This is kind-of the 'bubba' method, but lets you know exactly where your headspace is, assuming it isn't way long, bordering on the No-Go length.
Checking the headspace is actually easiest to do before you assemble the upper, or at least before you toque the barrel to the upper. Remove the ejector (you need the right size roll pin punch for that, as well as a spare roll pin), and extractor. This takes a little time, but makes it really easy to feel how tight the gauge is in the barrel without fighting the ejector tension.
titsonritz
01-06-16, 23:51
You don't need a bunch of different gauges, this one is all you need: 5.56MM MAXIMUM HEADSPACE GAUGE (http://www.brownells.com/gunsmith-tools-supplies/measuring-tools/headspace-gauges/colt-5-56-headspace-gauge-sku319418033-6646-15967.aspx)
Thanks for the headspace info, elephantrider.
You don't need a bunch of different gauges, this one is all you need: 5.56MM MAXIMUM HEADSPACE GAUGE (http://www.brownells.com/gunsmith-tools-supplies/measuring-tools/headspace-gauges/colt-5-56-headspace-gauge-sku319418033-6646-15967.aspx)
Same one I've used on a few builds.
What exactly is the remedy if you use that gauge on a new build and it shows you are out of spec.? The parts only go together one way... what exactly are you supposed to do after that? Get on the phone withthe barrel, upper and bolt carrier makers? Or is there some possible solution involved?
elephantrider
01-13-16, 11:34
Thanks for the headspace info, elephantrider.
No problem. I forgot to mention, that seeing exactly where your headspace is can help you in setting up reloading dies, assuming you will actually handload for the rifle.
What exactly is the remedy if you use that gauge on a new build and it shows you are out of spec.? The parts only go together one way... what exactly are you supposed to do after that? Get on the phone withthe barrel, upper and bolt carrier makers? Or is there some possible solution involved?
My most recent build would not have closed on that gauge, but then I wouldn't have known anything more about how under Max/Field my headspace was if I only had that one gauge. IMO, a Max/Field gauge is only useful if you also have the Go and No-Go gauges to cross check the headsapce with. Not closing on a Field gauge doesn't tell you if you are over the min/Go gauge. If you are using new parts and a Field gauge can close, I'd be bummed if that was my build, as that is somewhat long headspace to start off with.
As far as finding the culprit in an out of spec. headspace situation? I would venture to guess that the only solution is to cross check each part (barrel/bolt) with another of known good/correct spec. to find which one is causing the short or long reading as the case may be. Theoretically a short chambered barrel could be lengthened, but not much else could be fixed beyond that.
BTW, there are lots of different specs. on headspace gauges. It'd be good to know exactly what the length of your guage is, rather than just the GO/Field/No-Go designation.
http://www.ar15barrels.com/data/headspace.pdf
Bolt closing on a field gauge is bad. I need to note the user who's only using the field gauge on builds... In checking a new build I'm of the group that would have a go and no-go gauge. You can never be to careful when checking headspace on any firearm.
Then again, I deal in a lot of old milsurp rifles, so I'm one of those guys who has a pocket full of gauges when I'm gun shopping at stores and gun shows. I'm not buying something that's been shot out as I like to shoot my milsurps. I'd rather be safe than sorry, a face full of hot gas is the best case scenario for excessive headspace...
Read TM 9-1005-319-23&P and look at which gage is used, and how it is used as well as the remedies.
Bolt closing on a field gauge is bad. I need to note the user who's only using the field gauge on builds... In checking a new build I'm of the group that would have a go and no-go gauge. You can never be to careful when checking headspace on any firearm.
Then again, I deal in a lot of old milsurp rifles, so I'm one of those guys who has a pocket full of gauges when I'm gun shopping at stores and gun shows. I'm not buying something that's been shot out as I like to shoot my milsurps. I'd rather be safe than sorry, a face full of hot gas is the best case scenario for excessive headspace...
They let you completely strip a bolt to check the head space, when you buy stuff?
They let you completely strip a bolt to check the head space, when you buy stuff?
Most of my headspace gauges have cutouts for the extractor so you don't have to disassemble the bolt. I even have headspace gauges for the M1 Garand that I do not have the disassemble the bolt to check headspace. Makes it pretty easy and convenient. Depending on the dollar amount and "rarity" yes myself or the seller has completely disassembled rifles including the bolt to verify numbers matching, check bore and headspace, and to verify that it hasn't been "humped". It isn't that uncommon when you get into rarer all matching milsurps especially K98k Mausers. I even have throat gauges for some calibers to check throat readings. I know some guys who will slug the barrels on their milsurps to get the exact bore measurements.
Read TM 9-1005-319-23&P and look at which gage is used, and how it is used as well as the remedies.
I'll have to check that.
Based upon what you are trying to determine there are a number of different headspace gauges available.
NATO gauges (5.56 x 45 NATO chambers) are available from NATO Min (the minimum headspace allowable) to NATO NOGO and NATO MAX.
There is no need to purchase the NATO Min gauge. If your bolt won't close on a chambered factory round the headspace is too little.
The NATO GO gauge is designed for new builds and lets you know that your headspace is acceptable.
The maximum headspace NATO gauges are the NATO NOGO (1.4696) and NATO MAX (1.4736).
These were designed for testing used guns in the field to determine if they were still safe to shoot.
So if you want to know where your headspace falls within the acceptable range (1.4636 NATO MIN to 1.4736 NATO MAX) you would need a number of gauges. On the other hand if you want to know that your headspace is safe then you only need one gauge the NATO MAX ( 1.4736) available from Brownells (http://www.brownells.com/gunsmith-tools-supplies/measuring-tools/headspace-gauges/colt-5-56-headspace-gauge-sku319418033-6646-15967.aspx).
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