.30 Caliber M1 Rifle headspace should be between 1.940" (GO) and 1.950" (Field reject).  1.946" or less is arsenal re-issue standard.  1.950 or less in the field is fine.

Unless you have the military gage you will have to strip the bolt to check it.  There are really no safety issues involved here, as long as minimum chamber size is there.  General Hatcher used a grinder to induce massively excessive headspace without harm -- accuracy suffered, but that was it.

-- Chuck

NO-GO is a factory/arsenal gage designed to allow the maximum service life in the field.  Once the rifle is in your hands only the longer FIELD (Reject) gage has any meaning.

In order of length the gages are:

GO  (minimum chamber length for reliable operation)

NO-GO (maximum chamber length for new rifles or rebuilds leaving the factory/arsenal)

FIELD (maximum length).

The Army actually had over a dozen gages for the M1 Rifle.  I've only listed three of them for field service.  Match rifles can get picky about their headspace, but that's an accuracy not safety issue.  Match M1 Rifle has been an oxymoron for a couple decades, though .

You should be able to find commercial ".30-06" gages of these lengths.  As noted earlier you'll have to strip the bolt completely to check as the extractor and ejector will get in the way.  Use light finger pressure at most witht the bolt.

Do not sweat headspace!   It's a gunstore commando topic.  As long as you're shooting good, military M2 Ball it really doesn't matter.  M1 Rifles don't "blow up" from excessive headspace.  They may get sloppy accuracy, but that's the limit.

Note that M14/M1A gages are largely unavailable.  But the M14 GO gage is the same length as the SAAMI bolt gun NO-GO gage.  Use the length, not the commercial name.  Don't let someone try to sell you a new bolt for your M1A 'cuz it almost closes on a SAAMI Field gage -- it's in spec!

-- Chuck

As mentioned by Chuck, excessive headspace in an M1 allows the bolt to close fully.  In that condition, it is almost impossible to blow up, or even damage an M1, using standard ball ammo.  Case seperations, again mentioned by Chuck, are of course a distinct possibility.

To give you an idea of how strong the M1 action is, Gen Julian Hatcher, in a scientific series of tests, finally ended up loading an entire cartridge case with proof testing powder (normal amount was a small fraction of the entire case volume}.  Long story short, the rifle survived, and was still useable.

Quoted: Quoted: Case seperations, again mentioned by Chuck, are of course a distinct possibility. Try reading comprehension, he made no mention of it - I did.

Dear Garand06, please allow me to beg your pardon.  I am only human, and sometimes make mistakes.

Don't know about you, but I don't want 50,000 psi to suddenly become uncontained inches infront of my face.

Who's talking uncontained?  Isn't the bolt fully closed, and a cartridge of the proper head diameter in the chamber?  We're not referring to a cartridge that will interfere with the bolt closing.

I guarantee you it will split the stock, whether you'd be injured is another story, but better safe than sorry, and his advice doesn't cut it.

Didn't you say above what the rifle won't "blow up"?  which is it?

Quoted: To give you an idea of how strong the M1 action is, Gen Julian Hatcher, in a scientific series of tests, finally ended up loading an entire cartridge case with proof testing powder (normal amount was a small fraction of the entire case volume}. Long story short, the rifle survived, and was still useable. Go back and check again, I believe you'll find that although the action did not catastrophically fail, one of the bolt lugs did crack.  'Course if you believe Chucks' statement about headspace not mattering, you probably think this would still be a servicable "problem". Tim

True, the bolt lug cracked,  but you left out the rest of the story.  Hatcher then fired 5,000 standard rounds through the rifle with the bolt whose lug was cracked with no ill effects. (HNB, Pg 206)

Why did you leave that information out?

In my experience, replacing the bolt in a Garand is fairly straightforward.  Your experience may be different.  Regardless, my point was exactly that the action did not catastrophically fail.

Quoted: Quoted: Do not sweat headspace!  It's a gunstore commando topic.  As long as you're shooting good, military M2 Ball it really doesn't matter.  M1 rifles don't "blow up" from excessive headspace.  They may get sloppy accuracy, but that's the limit. --Chuck Granted the rifle itself won't blow up, but what about the likelyhood of having a casehead separation.THAT is the real problem with excessive headspace. That can cause you to be thankful you wore your shooting glasses and give you hours of fun picking stock splinters from your hands and arms. Tim

Interesting you should mention this.

I once had the experience of firing some crappy Izzy milsurp through a Modelo 1912 Mauser, made originally by Steyr, in Austria.

A couple of the cases failed catastrophically, with a longitudinal seperation beginning at the primer pocket, travelling radially across the case head, and forwards about halfway up the body of the case.

The net result was a slight puff of gas in my face. No drama, no explosion, no splinters, no nothing except a story to tell.

Point is, that a case failure of that kind, in a well-made rifle is no big deal as long as you are wearing shooting glasses.

Perhaps you are personally more familiar with rifles blowing up. If so, please relate your personal experiences.

Match shooters may want to keep their chambers between GO and NO-Go for accuracy purposes.

No shooters in the world worry about headspace but us!  Bubba Deer Hunter shoots hundreds of rounds a year and hasn't heard the word.  Nor has he (or any of us) been harmed by "bad" headspace.  Soldiers in Iraq who had their rifles checked last week (with Gage, Headspace, Field) can shoot thousands of rounds in the next 6 months without difficulty, even if their rifle would fail the Field gage this week.  

Even professional gunsmiths mis-use headspace.

A year ago I sent a new M1A receiver and a complete HRA M14 Rifle (less receiver) out west to get the "kit" assembled.  I received a phone call that I needed a new bolt (for $50 trade, no less) because my new HRA bolt would partially close on a SAMMI Field gage.  "Great!" I responded.  That means it's tighter than M14 NO-GO requirements.  [Long silence on their end, then]  Yeah, you're right.  Lots of folks would have bought a replacement bolt for a rifle meeting new specs from the arsensal.

I keep waiting for documented, primary source data of M1, M14, or M16 rifles blowing up due to excessive headspace.  And I'm sure I'll continue to wait.

Should we move to the nonsense differences between 7.62mm NATO and .308 Winchester and we shouldn't fire one in rifles maked for the other?    The bulk of "surplus" .308 out there is the result of pasting .308 stickers over 7.62mm marked boxes.  No, these rifles don't blow up either.

-- Chuck