what gauges do you use to check headspace on M14?

eltorro

eltorro

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I tried to build a nice kit to repair/replace anything that would (predictably) go wrong with the M14 on a long hunting trip. Most of the parts were related to the bolt assembly, so I got a whole new one.

I never fired the rifle with the new bolt, as I am not that senile yet.
How do you check your headspace on the M14? What gauges do you use? the US Go-Nogo ? the regular 308 ones?

My gunsmith here says he doesn't have them, and I'm too lazy to ship it to a more distant one.

What to use and where to buy it?

It would be nice to know for sure the rifle is safe to fire, and even more useful if not so.
 
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What bolt did you use as a replacement? Any real play in it when locked? I think the minimum guage you should use to check is a .308 winchester NO GO guage. You still want to be somewhere between NATO FAIL and .308 NO GO but I hope your bolt replacement went better than that. Ask your gunsmith if he has the .308 NO GO. He should.
 
You need a whole set of regular .308 headspaces for fitting a new bolt. Brownell's carries them.
"...the bilt assembly..." The what?
 
"the bolt assembly" sorry.... I stand corrected.

My gunny says he doesn't have any 308 gauges.
The replacement bolt is Norinco, same thing as mine.
 
I measure all of your fired brass cases (many of you ship 5 of them to me) using a RCBS Precision Mic in .308 of course. Many of you would feel that buying one of them at $ 65 may be quite an expenditure, so I did just that for the few times you need your chamber measure, just mail me 5 cases !!
 
He is a little concerned with firing the rifle before checking headspace. If there isn't real significant slop when you cycle the action closed, fire off 5 rounds and mail them to Hungry. I mean if the bolt has like 3/16" slop, your own judgement should kick in.
 
In the past, I recall chatting with NavyShooter. He reported some bolt slop while the bolt was closed or in battery. He figured about 1/32" of play give or take, of course. I miked his brass that he sent me from Halifax, Newfie Scotia and it miked to about 15 thou (Hey Brad, correct me if I'm wrong), just like we kinda guessed using the SWAG technique.

That's Scientific Wild Ass Guess for you non-technical types. LOL

Yes, that bolt slop is engineered into the design of the M14 rifle to allow bolt interchangeability in the heat of battle (or zombie attack).

For those of you new to this M14 game, my Douglas Barreled Norinco M14's (I had built 2 of them for myself) did NOT have ANY bolt slop and when I fired the brass, they miked to EXACTLY 0 thou or 1.630" on the SAAMI specification. Like my goaltending in ice hockey, sometimes it's better to be lucky than good.

Both my M14's had TRW bolts that had chambers right dead nuts on at 0 thou.... That's what happens when one uses a match barrel and a TRW bolt. Life is good. I sold both rifles .... ooops.

Cheers,
Barney
 
Thanks Hungry, like Ripstop said, I'm a little scared to fire it for five times and then sent the rifle or the five cases to you - depending on the aftermath.

But I shall be scared no more.
 
.308 gauges might close on a no-go gauge in the 'rinco. 7.62 should not close on a .308 field gauge. So, unless you switch to a USGI bolt, .308 gauges required should be no-go and field. If you want to swich to a USGI bolt, the go gauge may be used. So, get all three. Clymer ships to Canada. Make sure you test the headspace on a stripped bolt with a clean chamber. Use only light finger pressure when closing the bolt on the gauge - force nothing. The bolt is closed when the right hand lug bottoms-out and touches the receiver.

Please go here for a better explaination and pictures:

//hybrid.ualr.edu/satu/headspace.html

(http: in front of this address)
 
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Head space on an M-14 is NOT rocket science ...
[;{)

I use either a MILSPEC 7.62 NATO GO gauge or a COMMERCIAL .308 Win GO Gauge AND a set of automotive leaf feeler gauges. Of course, the .308 GO Gauge is nominally .0055" shorter. In essence, if you believe in SAMMI specs, the 7.62 NATO GO gauge is already OVER .308 NO GO ... but in the real world, I've seen M-14 rifles with MASSIVE headspace that functioned safely and flawlessly AS LONG AS YOU USED ONLY 7.62 NATO AMMO. The brass in 7.62 NATO is THICKER and HARDER than commercial .308 brass.

In the M-14 type rifles, more important than headspace is EVEN wear on the lugs, with MAXIMUM bearing on BOTH lugs.

The 7.62 NATO gauge has the advantage of being cut out for the ejector, so you don't have to strip the bolt to get an accurate reading, like you SHOULD do with the commercial .308 gauge. If you use a commercial .308 gauge and don't strip the bolt, the rather heavy ejector spring is pushing the gauge into the chamber - WAY out of touchy/feely specs.

ASSUMING [ and you know what that can do ] that the bolt lugs are square to the bore [ which can usually be determined by checking the wear pattern on the lugs ] stick in whatever gauge you have, close the bolt [ if you can ] then slip in the appropriate feeler gauge between the rear of the bolt lug and the right side of the receiver. Add the thickness of the feeler gauge leaf to the headspace gauge, and you have a very realistic guestimate of true headspace.

If you want to be TOTALLY accurate, buy the complete set of .308 gauges, stepped up in .001" increments ... but that will cost more than you want to contemplate. A well known M-14 poster here on CGN has a set ... maybe he will rent it to you?
 
eltorro
I've got a set of Forster gauges I'm willing to rent to you( Go - NoGo - Field). The rent will be equal to the postage paid on the package you received. You must return it, paying the extra buck for a signiture (I'm willing to trust you , but not Canada Post). PM me if interested.
Regards
Mike
 
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