Minimum safe headspace question

[rlelvis]

I have a bolt that is just shy of closing on a GO gauge, maybe .006 max between right lug and receiver. With the extractor installed and spring removed it will close on a HXP round with a little pressure. Question, is it safe as is? Could I get away with lapping to fit? Should I just find another bolt?

Thanks
Bob

[Orlando]

I would lap the bolt, but I'm a hack

[The Garand Guy]

You should either get a shorter bolt or ream the chamber. If you send me your bolt & $6 return shipping, I will gauge your bolt & trade you a shorter one.

[Orlando]

Tony
Being that close wouldnt lapping the bolt close on the gauge or is it to far?? Not arguing just curious

[timshufflin]

Tony
Being that close wouldnt lapping the bolt close on the gauge or is it to far?? Not arguing just curious

I don't think you'd have a problem at all.

[rlelvis]

Was leaning toward lapping the bolt but was not sure how much I would get. I am being generous with the .006 measurement, probably closer to .004 with a bit of pressure. I have done it with bolt actions before but never a Garand. If I do try it and don't get it to close on a Go gauge would the process effect using the bolt on another receiver?

I do have a couple of bolts to swap out. Was trying to get the closest fit I could on this one.

Thanks for the bolt swap offer and will keep it in mind as I figure out what I am going to do.

[The Garand Guy]

Lapping the bolt will cause it to close, but you will still have the problem of the spacing.

[Orlando]

Lapping the bolt will cause it to close, but you will still have the problem of the spacing.
Tony
How so, Please explain. I am always willing to learn this stuff

[The Garand Guy]

.1940 is the point of proper headspace. Yours is apparently short at .1039. If you lap the bolt lug, the bolt will close, but the headspace will remain the same, .1039.
As I said before, if you send me your stripped bolt & $6 return shipping, I will gauge it, & send you a shorter bolt, which should headspace properly.

[canes7]

Ream it... It's the right way to fix it (IMHO). Too much lapping and you'll wear away all the surface hardening.

[Dave]

First thing I would do is make sure your chamber is perfectly clean and that your not getting a false reading due to debris or a burr or ding. Inspect the chamber carefully with good lighting to check for anything. Also check the gage itself for any debris or defects. Next check the bolt lugs and receiver for the same thing. If everything is clean and ding free, I'd use prussian blue on the lugs/receiver to see what the contact looks like. If its good, ream the chamber. If its got a high spots then try lapping a bit or try another bolt. Your not that far off though.

[timshufflin]

First thing I would do is make sure your chamber is perfectly clean and that your not getting a false reading due to debris or a burr or ding. Inspect the chamber carefully with good lighting to check for anything. Also check the gage itself for any debris or defects. Next check the bolt lugs and receiver for the same thing. If everything is clean and ding free, I'd use prussian blue on the lugs/receiver to see what the contact looks like. If its good, ream the chamber. If its got a high spots then try lapping a bit or try another bolt. Your not that far off though.

I would go with this but let's address what Tony is saying. I think what Tony is trying to say is that even though you will get the correct headspace by lapping, you will still have more case base sticking out of the chamber than you should. Am I "on target" Tony?

Reaming will get the round in the chamber where it should be while lapping will allow the case base to protrude further and give you a case base that will expand easier, and cause less trips for brass. This can be a bigger problem if using commercial brass.

[The Garand Guy]

Lapping will not correct the headspace. The cartridge is still in the same position;only the bolt has been moved back.

[timshufflin]

Lapping will not correct the headspace. The cartridge is still in the same position;only the bolt has been moved back.

Tony, could you answer my question? If you lap a bolt, you are essentially shortening the lugs correct? You could have a bolt where the barrel was reamed for headspace, for instance a 12. Then you put in a 65 series and you won't make headspace because most 65's are longer. Now you could lap the 65 and make headspace or put in a slightly longer -12 and lap that. I'm confused Tony.

Headspace is the distance between the face of the bolt and the datum line, which is a circle of stated diameter, along the slope of the shoulder of the cartridge. If you change where the face of the bolt is, you are changing headspace.

One more thing, if you swap out a bolt for a shorter bolt as you indicated and suggested on page 1, how is that different than lapping a bolt and moving the face of the bolt back? Only difference I can see is now having lugs which may be missing case hardness.

[rlelvis]

OK I am on the road so I don’t have the Garand in front of me.

Dave, Thanks, I agree and did most, except for mark and check for contact.

This rifle did headspace fine with two other bolts I pulled from two other rifles. This was a bolt that I wanted to use that did headspace in another rifle but was close. My first thought was to lap it until it closed. It is very close to closing completely. Either way no need to touch the bbl.

Now I am second guessing what I thought would happen when I lapped to get it to headspace. In my mind if it closed on a GO gauge the space for the round in the chamber was sufficient. Now I am wondering if I am missing a bolt measurement that affects headspace or another dimension I was not considering.

I have always made sure they would close on a Go gauge and not on a NOGO gauge. If they passed these two checks I called them good and have never had a problem. What am I missing? I am all ears.

[Orlando]

I think I understand what Tony is getting at but we are talking such a small amount here that I cant see where lapping the bolt would hurt. Like already said its no different than using a shorter bolt??

[The Garand Guy]

If the chamber is properly reamed, lapping the bolt or switching the bolt for a shorter one will both work.

If the chamber is not properly reamed neither choice will work.

[timshufflin]

If the chamber is properly reamed, lapping the bolt or switching the bolt for a shorter one will both work.

If the chamber is not properly reamed neither choice will work.


EXACTLY, if the chamber is to the specifications of the rounds, lapping the bolt will work. I knew we would get to it.

[The Garand Guy]

It is better to switch to a shorter bolt, for as someone has already said , you might grind off the case hardness

[Dave]

If you have to lap a bolt to the point where you go past the hardness, you have some other serious problem.