M14s Headspace - Bolt play

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C9er

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Hi,
Do I need feeler gauges to measure headspace or is there another way?

What is acceptable headspace for a Norinco M14s?

In general should there be any play in the bolt when it's forward? For instance, when it's locked I can place my finger on top of the bolt and slide it back & forth . I would have to really ballpark it, but i would say I am getting about 1/8" of back & forward movement.

Thanks a lot.
 
You generally check by either buying/borrowing/stealing a set of nato spec guages, or measure your fired brass.
 
Canuck223 said:
You generally check by either buying/borrowing/stealing a set of nato spec guages, or measure your fired brass.
Click to expand...

So what should the case measure out to, and what would be the procedure for figuring what your headspace is? I know Hungry will do it if you send him five cases, but it can't be that difficult to do yourself, with a good vernier or micrometer.
 
Is that 1/8" of play with no round in the chamber? If it was that bad with a round, I'd suspect you'd be severely injured by now. That said, a headspace gauge goes into the chamber and the bolt is closed on it. It should close on the "go" gauge, but not the "no go" gauge, which is slightly longer. As far as measuring your brass, I don't think there's any way to do it with an everyday micrometer. Brass measuring devices like the one Hungry probably uses measure off the tapered shoulder of the round, and compare to a headspace gauge. If you're concerned, I'd either take it to a smith or send Hungry some brass. Either way is easy, and you don't have to guess.

Drew
 
I'm here if you want to mail me 5 pcs of fired brass. Most of the Marstar M14's have been averaging around 10 thou headspace above the SAAMI Spec of 1.630"... add those together and you have a headspace of 1.640". Make sense ?

My first of 2 Norinco-plinko M14's mic'ed to 17 thou (no joking). Once I dropped in a TRW USGI bolt and then fired some brass, the headspace was measured to 1.630" or 0 thou. A match chamber !!! Yeeee ha...

Remember all this bolt slop was engineered into the M14 system so that bolts could be swapped in the field.

Many of my real M14's mic'ed around 18thou to 20 thou. No joking.....

Hope this helps,
Barney
 
Sixty9santa:

I am using an RCBS Precision-Mic. It measures the headspace from the bottom of the case to the 'datum' line.

Frankly, in all my years of competition, I have never noticed a chamber getting larger and larger. By measuring the headspace , one can custom load (die re-sizing) their brass to that particular M14 so that one can reduce the stretching and re-sizing working of the brass. This results in longer brass life.

Make sense ?

Cheers,
Barney
 
Hungry said:
Sixty9santa:

I am using an RCBS Precision-Mic. It measures the headspace from the bottom of the case to the 'datum' line.

Frankly, in all my years of competition, I have never noticed a chamber getting larger and larger. By measuring the headspace , one can custom load (die re-sizing) their brass to that particular M14 so that one can reduce the stretching and re-sizing working of the brass. This results in longer brass life.

Make sense ?

Cheers,
Barney
Click to expand...

And the "datum" line on a 30-06 case is measured on the shoulder where a diameter of .375" would contact.
 
Thanks all. the 1/8'' of play is with an empty chamber :O

Hungry, I might just take you up on that offer.

One last question though, I read somewhere that with a match or close to match fit (+/-2 thou) you can't fire milsurp ammo??? If that's the case what would be the minimum headspace for firing milsurp would you say?
 
C9er said:
One last question though, I read somewhere that with a match or close to match fit (+/-2 thou) you can't fire milsurp ammo??? If that's the case what would be the minimum headspace for firing milsurp would you say?
Click to expand...

Cartridge dimensions are always a little less than (minimum) chamber dimensions :eek: (makes sense?) Therefore, go ahead and fire any 308 or 7.62NATO cartridge in your match chambered Norinco. Milsurp ammo especially is usually undersized so as to feed reliably in MG's and other military weapons. For some more info, go here: http://www.fulton-armory.com/308.htm
 
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