M1 carbine headspace
I am a little new to semi autos so I thought I would seek a little advice here. I picked up an M1 carbine barreled receiver made by Iver Johnson that was missing a bolt. I have 2 bolts here. I do not have headspace guages. I had a gunsmith friend in FL that used to use 3 layers of masking tape on the rear of the case as a no go gauge if he did not have the correct one. On a bolt action the bolt should not close on a case with the tape on it. I tried some dummy rounds with the tape on it and both bolts close fully on the tape. Should I be leary of firing the gun like this? I would think the bolt should not close fully with the tape on?
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you are using a case to check headspace...not a good idea, cases vary greatly (this is a 'field expeadent, and not a good one). there problably is a good reason you got that as a barreled receiver (out of spec.) 0 -
rigelb79,
Headspace for the .30 Carbine is from the boltface to the case mouth with the bolt closed. Here is the Forster .pdf explanation for the gauge and its use:
http://www.forsterproducts.com/client_images/catalog19938/pages/files/30_Carbine_Headspace_Gage_HG0030-001.pdf
I agree with the term 'field expedient' with regard to the use of tape. Real gunsmiths use real gauges of known dimensions, not tape or little pieces of shim stock. Properly manufactured gauges should last nearly forever when taken care of properly. Yes, they are an investment but what quality tool isn't?
You can rent gauges from:
http://www.4-dproducts.com/
http://www.reamerrentals.com/
Best.0 -
On the GI bolts there are longer and shorter bolts and you can get a different headspace with each bolt. I don't know weather Iver Johnson make the dual spring model of the carbine, I know that the Universal dual spring Carbine take a complete different bolt. I would think that if you find a local gun smith to look at your receiver, I don't see how he should charge you very much to check it is very easy. With out over doing the warning, you could have a failure using short cuts to check critical measurements.
Emmett0 -
M1 carbine is a pistol round, not a high power rifle round. I have never seen a headspace problem on a USGI M1 carbine. An IJ is not the same, but is an excellent quality commercial copy.
Having said that, the book answer is that you should check head space with gauges on any gun when you install a new bolt.
Neal
EDIT: To remove the extractor & ejector, you need a bolt assembly tool. Maybe it would be best to take the whole thing to a gunsmith.0 -
I think I'll rent the guages and see what that yields. If it comes up excessive then I'll take it to a pro. Thanks for the help. 0 -
Bear in mind that you do not check headspace by slamming the bolt on the gauge as though it were a cartridge to be fired. To say that a gun accepts the gauge, the bolt must close on it with fingertip pressure. Best to take the extractor and ejector off so there is no spring load. 0 -
Ok then with that in mind would it be best to remove the spring from the slide and just close the bolt with finger pressure. 0 -
I would. 0 -
quote:Originally posted by rigelb79
Ok then with that in mind would it be best to remove the spring from the slide and just close the bolt with finger pressure.
If you are refering to the recoil spring, yes. And then remove the entire slide (operating rod) from the rifle. Now..let's start the gauging procedure:
Gotta remove the extractor (and the ejector). The extractor could have an out of 'true' claw underneath, and will give you an innacurate reading.
Get the bolt tool. Get the gauges (rent, buy, or steal)[:0]
Strip the bolt and perform the gauging procedure without the operating rod installed.
Get it done correctly the first time. Best way all around.
Best, Joe0 -
Proper Carbine headspace gages have the rim removed to extractor claw depth to avoid removing the extractor and its' flying spring and plunger. 0
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