Which headspace gauge to buy?

[borderman]

A machinist is putting a Douglas XX long-chambered barrel on a Mauser action for me. I am supplying the barrel and headspace gauge. I thought a GO gauge was proper but reading the Brownell's catalog has got me confused. It states a GO gauge 'gives the SAAMI recommended minimum chamber depth'. However the NO-GO gauge is 'slightly shorter than the SAAMI recommendation to give a small safety margin'. I thought the NO-GO gauge was longer but what do I know. Any recommendations?

[mozark]

I've always chambered to a "go" gauge. Minimum is minimum. I'm not sure I understand why minimum headspace would require a further safety margin.

MM

[Char-Gar]

The bolt should close with just a slight drag/feel on the GO gage. It should not close on the NO GO.

The GO is minimum headsapce.. If the bolt will not close then the chamber is too short.

The NO GO is indeed longer than the GO but Brownells are a hair shorter than spec for a NO GO gage, not shorter than the GO gage.

[Rottweiler]

The guages should be bought and used as a set.

Correct headspace is when the bold will close on the GO guage bet not close on the NO GO guage. The guages can be bought seprately but if you do that make sure they are made by the same manufacturer.

They are supposed to be made to very exact dimensions, sometimes different manufacturers may vary a little one way or another. If one varies one way and the next varies the other way you could end up with too much variation to be accurate and/or safe

[versifier]

You can rent a set from 4-dproducts.com

[borderman]

Many thanks for the replies guys. I am going to buy both gauges as suggested. Thanks Chargar for the NO-GO explanation. Can't do the rental Versifier since I have already been warned the machinist is slow and only works in his shop when it is warm enough so scheduling the rental would be tough.

[carpetman]

Uh urr--What is headspace?

[danski26]

It's the room between the top of your head and the top of the door way when you walk through.......sorry i couldn't resist :-)

[Scrounger]

Uh urr--What is headspace?

CarpetDude as a callow youth:

[KCSO]

You can set headspace with just a go gauge, but this doesn't take into consideration the normal deviance of factory ammo. You set a rifle for just minimum and some day out in podunk you will buy a box or Remchester 30-09"s and sun of a gun they won't fit, cause the factory was having a bad day and they were made 2 thou too long. So for sporting arms you use both gauges to allow for slight differences in ammo. Target guns are a different matter and I have chambered guns to a specific sized shell or reloading die. I have a factory Ruger 77 that won't chamber PMC ammo at all, the chamber was cut minimum and the PMC's are too big.

[mozark]

Deviant factory ammo, my thoughts exactly.

MM

[waksupi]

One thing I see a lot of, is people wanting match chambers, for thier hunting rifles. Bad idea, in my way of thinking. I'd prefer a little slop, for store bought rounds, or some dirt in a chamber.

[felix]

Waksupi is correct, folks! The smallest chamber for a field gun should be SAMMI's minimum, and no less than that! ... felix

[Ricochet]

The smallest chamber for a field gun should be SAMMI's minimum, and no less than that! ... felix
Which, of course, is the point of the "GO" gauge.

[KCSO]

I won't do a match or custom chamber for anything but a bench gun. Waksupi is right. The British specs call for a 074 headspace on a .064 rim and although that is a little generous in my opinion you never find a 303 that is hard to chamber a round.

[Char-Gar]

The boys are of course correct that with a minumun chamber you can run into factory ammo that is half a hair too long. They are also right that gunsmiths shouldn't or won't put a minimum chamber...UNLESS.. the customer requests it that way. Put a minimum chamber on the average guys rifles and you are apt to have it back in the shop along with a pissed off customer.

That said, I have put more than one minimum chamber in my rifles. That is the way I want it and shoot very very little factory ammo. I would never take any rifle hunting without running each round through the chamber to make certain everything was kosher.

I have never had a "ready load" hang up in a minium chamber, but as I said, I don't shoot much of such ammo.

When, I was a kid and shooting service rifle matches with the 03 Springfield, the local gunsmith had a box of bolts, maybe a hundred or so. When we got a new rifle, we would go by his shop and with a GO guage try the bolts in the box until we got one that would produce a minimum chamber. We would then toss our bolt back in the box and pay the Smith $3.00 for the borrow of his gage and swap.

These rifle went to Camp Perry and other places where LC and FA NM ammo was available and we never had a problem. I can't prove a mimum chamber provides better accuracy, but we sure thought it did, "back in the day".

[Mar354]

I must agree all the way with Felix and Ricochet. What I think some of you are talking about is under the minumum standard. If you can't close the bolt or even feel a drag when attempting to close on a go gauge, you have a chamber under the minimum industry standard. I graduated from a civilian gunsmith school 31 years ago and have been working in the trade full time since then. When I was taught to chamber a rifle, the process was always to close freely on a go gauge and to have the bolt stop its closing movement just as the bolt started to cam over on the no go gauge. If you could not accomplish this you were definitely on the instructors bad boy list. If the bolt would close about half way and then stop, you are still well within specs of proper headspace, but this would not do for a good grade in that class. When I began working, being a high power competitor, I built over the course target rifles on quite a few different actions. I chambered the rifles as I was taught with the tightest headspace. I soon began getting complaints that in the 200 and 300 yd. rapid fire stages they would get some rounds that would be hard to open to reload for the next shot. When you shoot rapid fire with a bolt gun the thing must work smoothly or you will not get all of your string off before the targets disappear. After a short investigation, I realized that the tight headspace was the problem, so I re-reamed them just so the bolt would go to about the half closed position and the probem went away. I never had any of these shooters then complain that the accuracy was any less, and when you shoot out to 600 yds, I think this would be apparent if it did. I later went to work in a military shop and soon discovered that most military headspace gauges are longer than the one used for the same caliber in the civilian world. Of course we are not talking about target rifles here, but in the 7.62 mm Nato are both well over the specs for the .308 no go. These 7.62 gauges are both no go, but one is for overseas use and the other is for training use only, but both are well past what we consider maximum headspace in a sporting rifle.