Anybody ever use a no-go tester

Got me a new rifle and was doing some reading up about em and it seems that one thing that was highly recommended was a no go tester has anybody used one of these before?

The rifle is a russian surplus Mossin-Nagant 7.62X54 rifle.

found this

http://www.surplusrifle.com/shooting/headspace/index.asp

it's all about your M-N rifle

What did you have to give for the M-N? I see them cheap on gunbrokers and ammo is cheap too. I've been thinking about buying one. I guess they are only accurate up to about 200 yards though. Same with the Jap Arisaka. Both are well built guns though.
Not sure on the go-no go but I guess it's pretty simple. Why do you feel you need the guage, has it been re-barreled?

Got it on sale at the local gun/sporting goods store for 80 bux. They normally sell for about 120 bux.

I guess I was reading up on them on the various sites and they were saying that it would be a good idea to do since its left over military surplus.

More of a safety thing to do before firing than anything else.

The no-go test test the max allowed headspacing. I guess if you can close the bolt on the no go tester its unsafe to use.