Springfield 1903

[ssgross]

What gauges and where to buy them?

EDIT: I should have started pointing you to read about what headspace is first, since you don't have knowledge of the gauges.
https://en.wikipedia.org/wiki/Headspace_(firearms)

You have a few options. At minimum you need the field gauge.
https://www.amazon.com/Forster-Produ.../dp/B004LHCUUG
Strip your bolt down (take out the fire control and remove the extractor). Clean your chamber, insert the gauge, and gently close the bolt. don't force it. If your bolt falls short of closing, you're in business - mostly. The field gauge is the max safe headspace. If your bolt closes, the rifle is unsafe and you should not attempt to fire it.
Ideally the bolt won't close on a no-go gauge either.
Now...if someone rebarreled your rifle and didn't check headspace, it is possible that your bolt won't even close on the go-gauge (min headspace). I've had this happen before as have others here. It's cheaper to just get the set of gauges go, no-go, and field then one at a time.
https://www.amazon.com/Forster-Produ.../dp/B084C37PWR

If you only want to buy one gauge, there is a field sobriety test you can do to get an idea of where it's at. I say sobriety because make sure you are entirely sober when you purposefully remove the fire control - firing pin (striker, whatever your vocabulary), spring, etc), and put those parts away in another room out of your reach. Keep the extractor on. Then take a factory round, insert in the chamber, and make sure your bolt closes. You can then use a piece of tape on the base of the cartridge. Depending on the thickness of the tape, you should feel your bolt drag on the tape as you try to close it. I think aluminum tape is like 0.003 thick. If your headspace is good, you will certainly feel the bolt drag on 2 layers (0.006). Basically, if the bolt drags on a round you need a go-gauge. If it drags on 1 or 2 pieces of tape, you need just the no-go. If it doesn't drag until 3 or more, you need a field gauge. For 30-06, the difference between max and min headspace is 0.010, so you see the tape trick is just ball parking within that spectrum.

Some might balk at testing with a live round - but it is pretty common for handloaders to do the same on cartridges coming off the press. Again...NO FIRE CONTROL anywhere close to the rifle when using a live round.