Are all go/no go guages created equal?
- Thread starter pyscodog
- Start date
Yes, that is to say that i.e. a 308 Winchester go gauge will measure the same from datum line to base no matter who makes it. At least they are all supposed to...not saying there can never be one made that was not the correct length, but it is a gauge and has no other purpose but to be "right." They are made to SAAMI specs for a given cartridge. It's a stupid slug of metal cut to a certain given length and if it is not the correct length then the manufacturer could be liable. I have used many different brands and calibers and never yet seen one that was not correct. Again, not saying it cant happen...just extremely very unlikely. One brand must measure the same as another, no matter who makes it because there is only one purpose.
MotoHunter
New member
all off the shelf gages should measure to SAMMI's maximum chamber size for a given cartridge. Then there are the custom gages made using the same chamber ream that the gunsmith making your custom rifle used to ream the chamber of your new rifle. They are an exact fit obviously.
I think your question is will a Forster and PTG headspace gauge measure the same. All gauges do not measure SAMMI maximum chamber size. They measure somewhere in the tolerance range between maximum and minimum. Some measure at the high end of the tolerance range, and some in the middle. You should never mix brands of gauges and the simple reason is tolerance stacking. If you use a PTG go gauge, use a PTG no-go gauge. Same with Forster, Clymer, Manson or whoever. If you look at the SAMMI drawing for a .308 Winchester you will note that the maximum headspace dimension is 1.640 and the minimum headspace dimension is 1.630 (bolt face to datum line). That's 0.010" difference and I don't think there are any go, no-go gauges that have that much "delta" in them. It's usually on the order of about four thousandths, unless of course you use the "field" gauge. Not trying to be a smarta$$, just trying to share what I have been taught over the years.
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Can I recommend that you take your go gauge, put two pieces of cellophane tape on the back of the gauge where it contacts the bolt face, and see if the bolt will close without a lot of force on the bolt handle? If that does not yield acceptable results I will be glad to let you borrow my .308 Winchester gauges (mine are Manson) and see what you get. If the bolt closes on the Manson no-go you might want to have your gunsmith take a second look at his measurements. Lots of "stuff" happens when you torque up a barrel to an action, but usually in the other direction.
I would like to add that I am not suggesting that the PTG gauges or reamer were not correct. PTG makes some really fine stuff, I know, I own some of their tools. But we should never underestimate the human factor.
I would like to add that I am not suggesting that the PTG gauges or reamer were not correct. PTG makes some really fine stuff, I know, I own some of their tools. But we should never underestimate the human factor.