I removed the barrel on my Sako TRG 22 which was a task in itself.

I've got a KRG 6.5 CM barrel, KRG barrel nut, barrel nut wrench, action wrench, barrel vise, torque wrench etc.

I am waiting on my headspace gauges.  I will have a go gauge, no go gauge, and a field gauge.

Do i just thread the barrel in until it touches the go gauge?  Back it off a little?  

Ive never bothered with checking the headspace on AR15's, but obviously this is a little different.

I'm also interested in this.  I have always sent bolt guns off to a real gunsmith.  AR-15's don't seem to be so picky.

I've never taken an Armorer's or Gunsmith course, but this is what I do

Remove Ejector
Get barrel threads started in receiver
Snap Go gauge into extractor/boltface and lock into receiver
Thread barrel until you feel the slight resistance of gauge
Thread barrel nut until just snug, but not tight (this puts additional tension on threads)
Open and close bolt, to feel gauge's "tightness".
Adjust as necessary.
Tighten barrel nut and check No-Go

It's a bit of a dumb process to use two incorrect gauges to shoot for the middle.

In a perfect world, I would have a "Correct" gauge that I would tighten the barrel nut on. It would be several thousandths over the go gauge.

What alot of us do is use a go gauge plus scotch tape which is remarkable consistent at .002.

If you are competent to do the job, the no go gauge is really not involved. Its "facts in evidence" if you've set up directly off the go gauge.

To me, no go and field gauges are for checking an unknown to you firearm, not a barrel you installed.

Aren't you going to end up with a long chamber doing this?

I've always thought that closing tightly on a GO was best. Or even just starting to rotate into battery but not fully, because most produced ammo is shorter than a GO.

It’s the brass not the ammo. Factory ammo tends to be a little short for enhanced compatibility.

For me, since I am reloading usually day 1, I set the headspace. I’ve had tight headspace ar barrels and they were a pita to reload. You had to cam over with off the shelf dies to achieve .002 to .004 thousandths of shoulder bump. When you are camming over it’s less consistent round to round.

So you got die companies trying to make it foolproof, barrel makers balancing out of the box accuracy and safety, and different barrel nut systems.

It’s been awhile but if I recall correctly, savage style nuts draw it out .002 when torqued and rpr stays the same or draws in a bit.

Either way if plus .002 or so in a tolerance that allows .006 in x caliber.

Since most reloaders are sizing the shoulder minimally each time, their brass is always going to be whatever they set it off the shoulder. Typically .002 for bolt and .004+ for gas guns

You guys tell me if any of this sounds incorrect.

I agree. I use the Redding Comp shellholders; the +0.006" for my ARs. A little longer than ideal for a case's first firing. I'd prefer a slightly snugger headspace that required a +4 or 2 thou, but better than right on minimum.

When you set it up, avoid trying to use 'minimal' headspace. You want it right in the middle of the range, or on the longer side if required.

Zero headspace sucks lol.

As an example, SAAMI spec for 6.5 CM:
GO = 1.541"
NO-GO = 1.545"
FIELD = 1.549"

It depends.
I have a Savage 10BA I bought used in “like new” condition.
I bought this rifle because my very first precision rifle was a Savage 10BA that was an excellent shooter.
I shot out the barrel of that one and while trying to find a replacement barrel (in Canada) I bought this rifle.
I found a replacement barrel less than 24 hours after buying the rifle.

Upon bringing home the used rifle I cycled the bolt and the AccuTrigger tripped. Trigger set too low I though. Removed action and adjusted trigger but something seemed off.
I find bolt handle finger tight, firing pin protrusion way over spec, order of assembly on bolt head wrong.

I finally put everything together properly. Load 20 rounds into new Lapua brass and go test fire the rifle.
Everything looks good.

I received the new barrel for the other 10BA and once I finished installing it I was curious about the headspace in the basket case rifle.

The bolt won’t even rotate 1/4 the way down on the GO gauge.
I took one of the fired cases and compared it to the GO Gauge and it’s 0.002 under.

Now do I leave it as is or increase the headspace?
I don’t use factory ammo and every precision rifle has its own sizing die.

Use Redding sliding sleeve type dies with neck bushings and  cut the die with the chambering reamer.
Then use the neck bushings.