Keep researching! I have been reading these forums for several months. There are not a lot of postings on the subject, but they are all strongly opinionated. Fulton armory claims that all chicom m14 are dangerous. I doubt that. Fulton also claims that Smith does not do an appropriate job. However, Many people claim that Fulton did an excellent job for them. Some people claim that Smith did a good job. I would consider the option of buying a USGI bolt, and have a local smith do the fitting. Apparently, the bolt cannot just be dropped in. The prevailing philosophy is that the breach has to be lapped to fit the particular bolt.
I understand it is better to swap the barrel and bolt together. Something about the GI boltface not matching correctly with the ChiCom barrel face. Still some lapping involved supposedly. If you understand how to check the headspace properly on a M14 it should be safe to shoot the rifle untill the headspace begins to go south. Supposedly the bolts are WAY soft and have bad geometry. Thx-Ace
You must remove the extractor from the bolt and then check the headspace. The extractor holds onto the headspace guage and my cause an incorrect reading. I will not tell you how to remove the extractor because I have never done it but a GI M14 field manual has the instructions (this is even available online at the ARMY doncument site I believe). You must use either the combo tool (difficult) or a bolt dissasembly tool (easier) to remove the extractor.
You must remove the extractor to check the headspace on the M1Garand and Mini14 also.
I am used to difficult disasembly. But what, exactly do you measure? Is a special guage required, or can you use standard (what do you call them, spark plug type? guages?) I am supposing you measure the gap between a fully seated cartridge base and the bolt face?
Im sorry. I thought you wanted to know the specific way to check the M14 vs std rifles.
To check the headspace you use headspace guages. They are precision steel guages shaped generally like a cartridge and have specific tolerances. Generally you use a set of three (go, no go, and field). You insert the guages like you would a cartridge and try to close the bolt.
The bolt should close on the go guage w/o resistance. The bolt should not close on the no go guage. The field is a little longer than the no go (it is the maximum safe length ) and if the bolt will close on the field guage the headspace is unsafe. The go and no go guages are generally used when installing a barrel. The field guage is generally used to check the headspace of a used weapon.
Now you can see why the extractor must be removed. The extractor might hold the headspace guage forward of the bolt, giving a false reading.
Is it more clear now?
BTW I am not a gunsmith, I just have learned a little from some friends, good email groups and books. So my opinion is worth what you paid for it!
Here is a field expedient way to check headspace. It's not the final word, but it will get you in the ballpark.
Insert an unfired LC cartridge in the chamber (minus bullet, powder & primer of course!). Next, insert your stripped bolt and apply slight, steady forward pressure on the bolt. Using a thickness gauge, measure the gap between the right lug and receiver. A measurement of .001-.002 is optimum, .003-.004 being average. If you handload, anything from .006-.008 will lessen brass life. Anything at or above .010 should be considered dangerous. I am not a 'smith, but I got this from an old armorer. Hope this helps.