Using the stoney point "Head'n Shoulders" cartridge headspace gauge (as sold by sinclair int) I get a reading of .006 between a new case and one fired in my rifle. Would this be considered excessive headspace? The rifle is a brand new Remington 700 in .270 Win.. Also how accurate do you think these gauges are. Is there a better way for a lay person to measure actual headspace. I do own a couple of dial indicators and depth gauges.

Turkeyshooter---

Anything over a "GO" gauge is "excess", but the tolorence allowed in rimless cartridges is usually .007. I've seen new Remingtons be as much as +.012.

The best way to measure headspace is to pull the barrel and measure using a GO gauge and depth mic.

An alternate is to remove the ejector and firing pin assembly and measure the fore and aft movement of the bolt body with a GO guage chambered.

If you really want the recipe for accuracy out of your rifle, you should keep the headspace to no more than .002 max. Anything much over that causes the case to move too much to conform to the chamber in a concentric manner everytime it's fired. Some guys like to let it hang out there a little further, but the rifles best accuracy can't be obtained if you do so.

Headspace is the relationship between the cartridge and the chamber. It takes two to tango. New brass or ammunition may or may not be within "specs", so comparing the brass and the chamber only tells you that one of them is too little or the other is too big. These days, it would seem that you are fortunate to only find an .006" difference.

Rifle manufacturers want ammunition to chamber easily in their chambers, and likewise ammunition manufacturers want their ammunition to chamber freely in all rifles. Ever once in a while someone will encounter a brand of factory ammunition that chambers with a little resistance in their rifle and boy, do you hear bitching and moaning when that happens! Since the vast majority of factory ammunition is never reloaded, the rifles come with long, fat chambers and the ammunition comes in a miniumum dimension, and all of the once-a-year weekend hunters are happy.

My advice is to disregard the relative headspace on any chamber and start from day one by resizing your brass to minimize headspace. With a 270, run it over a .284 or .308 expander (or start with .30-06 brass to begin with), then squeeze it back down with a FL sizer, but only enough that it fits in your chamber with the slightest of resistance. Now that it is headspacing on a "false" shoulder, when fired you will have no stretching in the web area and will have brass perfectly tailored to your chamber.

By the way, most rimless cartridge chambers are a better fit for factory brass than belted magnum chambers. Remington makes chambers for the belted series that you can practically throw the cartridge in sideways. They figure that for headspacing there's the fail-safe of the belt, so they start with chambering reamers that are way-oversized. That way, they get many more chambers out of the reamer before it wears down below minimums. I've seen fired belted cases that would only go one-quarter of the way into the FL sizer before the shoulders hit the walls.

Went thru all this BS a few years back. I found most new ammo ( non belted ) was -.002 in size. If yours fired brass is .006 different your chamber is only .004 from the minimum. They can go +.010 ( some are even worse) and be within specs, so you have one of the tighter chambers. I always set my FL sizer die .002 less than my chamber. Remember if you vary from the -.002 factory ammo the bullets you load may not fit any other rifle you have.

JBelk gave you sound advice. The only way you can reliably measure your actual headspace is by yanking the barrel and measuring the protrusion of a headspace guage from the barrel face using a depth mike. You then need to measure the distance of the front action ring to the boltface( you will probably need to average this value) and measure the distance from the barrel face to the shoulder( again an average). Only From these measurements you can figure out exactly what your headspace is.
In most cases if you use fireformed brass, you will be fine and IMHO you won't gain much of an improvement in accuracy by the tighter headspacing of a factory chamber. A custom chamber is a different story, but not a factory one, for all the reasons listed in the other posts.
If the gun shoots acceptably to you don't sweat it!-Rob