I would like to know the length difference between the Go gage and the No/Go gage on a .50 Bmg.

I have the No/Go gage and I can barely close the bolt now. Being cheap I don’t want to spent $50.00 on the go gage, so I would like to know the length difference between the two, then I will surface grind the recoil lug to split the difference.

Buck,

quote:

Originally posted by Buck3:
I would like to know the length difference between the Go gage and the No/Go gage on a .50 Bmg.

I have the No/Go gage and I can barely close the bolt now. Being cheap I don’t want to spent $50.00 on the go gage, so I would like to know the length difference between the two, then I will surface grind the recoil lug to split the difference.

Buck,

You can barely close the bolt on what, the gauge or a round?

quote:

You can barely close the bolt on what, the gauge or a round?

The No/Go gage.

When you say it barely closes do you mean that it JUST closes are that you can close it with difficulty?

buck

Are you sure you are using that gauge correctly? You shouldn't be using ANY force whatsoever. Either the bolt will drop on the gauge or it won't. If it doesn't, the headspace is OK.

The difference between a go and a no-go is usually .004 to .006 regardless of the cartridge.

Ray

quote:

When you say it barely closes do you mean that it JUST closes are that you can close it with difficulty?

You can close it with difficulty, but I don't have to give it a lot of force.

Buck

Closing a bolt on a gauge "with difficulty" is giving you a false reading and may be damaging the chamber, the gauge, or both.

Think about what you are doing. You are forcing a hardened steel gauge into a softer steel chamber. Even if the difference is only .002 to .004, something has to give.

Ray

The gauge is called a "NoGo" for a reason. I hope you didn't take the surface grinder to the lug yet.

I don't think it was hard enough to do any damage. It felt more like shell that was a hair bit too long but would still chamber fine.

Buck,

quote:

Originally posted by Buck3:
I don't think it was hard enough to do any damage. It felt more like shell that was a hair bit too long but would still chamber fine.

Buck,

Buck

Not quite the same thing. If you have enough leverage in your bolt you can actually resize a case with excess headspace. Not so a hardened steel gauge.

The difference between a chamber reamer and a sizing die reamer is only about .002.

To use a gauge you need to strip the bolt of all springs, extractors, ejectors, etc etc. That way, the only thing you will feel will be the gauge itself. On the GO gauge the bolt handle should drop closed all by itself without any help from you. On the NO GO it should drop only partially (or not at all).

Ray

This is why God created gunsmiths. Please do yourself a favor and pack that 50 bmg up and send it to a real smith like Westpac who knows how to properly use the tools and not injure the rifle in the process.

If you had to use any force to close your bolt then it would have passed the no-go test. You should just let the stripped bolt try to close on the gage under its own weight if the handle stops before it hits the receiver then all is good.

I know without being able to let you feel it yourself its hard to explain to someone how much pressure is on it. No I’m not a certified gunsmith but I have rebarreled a few guns, and build this one with the exception of the barrel.

http://i148.photobucket.com/albums/s13/leebuckley/50bmg.jpg

Without the guts in the bolt the handle will not drop completely, but with just a little pressure you can close it. I have been working in the metal trades long enough to know it is not .002 worth of interference fit (hardened steel against hardened steel) maybe .0005.

Thanks for the replies,
Buck,

quote:

Originally posted by Buck3:
Without the guts in the bolt the handle will not drop completely, but with just a little pressure you can close it. I have been working in the metal trades long enough to know it is not .002 worth of interference fit (hardened steel against hardened steel) maybe .0005.

Thanks for the replies,
Buck,

Buck, when you say "You can close it with difficulty..." that sounds like more than a mere .0005 crush. Anyway, if the bolt won't close on your No Go gauge without help, then you are probably good to go. But if you are concerned, you can peel a couple of thousandths off the breech face and the barrels shoulder. That will close the distance. When you are playing with a single shot with that volume of pressure, it is better to have too little headspace than too much.