Searching for a video of how to...

[carwashchris]

Check headspacing on a M1. Tried the search feature but nothing, thought there might be a sticky.

Chris

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[imarangemaster]

Not a video, but great article on using gauges on the CMP page from their armorers. It is for M1 Garand, but the Carbine is done identically.
http://www.odcmp.org/0309/default.asp?page=M1HEADSPACE

[carwashchris]

Thanks that helps. I guess the only adjustment then is to swamp bolts untill you get a GO !

Not a video, but great article on using gauges on the CMP page from their armorers. It is for M1 Garand, but the Carbine is done identically.
http://www.odcmp.org/0309/default.asp?page=M1HEADSPACE

[shadycon]

Do you have a problem or just curious ? Has someone changed the bolt or barrel? The gages arn't cheap and should come with instructions.GK

[carwashchris]

Some times I get a few light primer strikes that don't fire it's factory ammo so Im assuming the case length is correct. Just looking for other possibilities. Chris

Do you have a problem or just curious ? Has someone changed the bolt or barrel? The gages arn't cheap and should come with instructions.GK

[Badger]

Here's an interesting general head spacing video in the Gunsmithing forum which I'm not sure you'll find helpful or not...

Head Spacing (mini lesson) - AGI Gunsmiths

Regards,
Doug

[shadycon]

Have you looked at the fireing pin closely for wear? Do you have light and heavy strikes? What make of ammo? Do you have a way to measure the cases just to see if they are correct? GK

[DaveHH]

I bought a couple of spares a few years ago and one was eroded and worn beyond belief. You had to look at it under a strong glass to see it. The FP was one of the problem parts with carbines due mostly to poor heat treatment.

Headspace gauges are available from Midway for about $30-35 each. You need a go and field. They do not require a bolt disassembly to work. The most important and dangerous condition is not a carbine with excessive headspace, it is a gun with too little headspace. Remember to use only light hand pressure to measure. Do not let the bolt slam onto the gauge.

[CrossedCannons]

A slightly less expensive way to check it yourself (if you already have reloading equipment) is to buy a chamber length gage from Brownells for about $5. It's like an all-in-one variable length headspace gage. With it, you can measure the actual length of your chamber instead of just checking its length at just two points, go and no go.

One of the 2 B/R's (aka tomato stakes) I purchased a while back from the CMP was tagged "No H/S". It of course closed readily on a commercial field gage (standard 1.299"). A USGI "field" gage is a bit longer (1.302") so I had hopes the B/R was still OK but good luck finding one of those. Using the Brownells/Sinclair gage, I measured the chamber, and wouldn't ya jus' know it, 1.302" exactly. Maybe fixable, maybe not.

[INLAND44]

First thing I would do is disassemble the bolt. Clean FP and FP bore, then measure FP protrusion and compare to the specs. Assuming the FP now reaches adequate protrusion, finish cleaning the bolt. Use Miltech 1 grease in the extractor and ejector spring bores. Assemble the bolt and lightly oil the rest of the bolt and parts. If this doesn't solve the problem, take the carbine to a gunsmith who is familiar with them and have it gauged. It's possible somebody dropped a bolt in it without gauging it, in which case you'll have to replace the bolt. It is also possible the barrel is not installed correctly - look at the bottom of the receiver/barrel for the index mark to see if they are in line. But Occam's Razor says it is most likely a FP protrusion problem or a hammer spring problem. Really, you have to analyze the whole function of the trigger and hammer to make sure you're getting adequate power to the hammer. While I'm thinking about it, does your bolt always fully rotate into the locked position? What I'm getting at is you could get a light strike on the primer on every round that chambers as the FP hits it lightly with the closing bolt. But, if the bolt is not fully locked, the hammer is blocked from hitting the firing pin. So you then open the action and see a light strike, thinking its a FP problem. Military ammo for self-loaders typically uses harder primers to prevent slam fires with floating FPs.