RC, I hope I don't come across as undermining you, based on our post counts this very much more your sandbox than mine. I just try to share what I feel is the safest and most thorough method of going about things when we are dealing with issues like case rupture. I just feel it would be a shame if the rifle passed this test and then the brother had issues later on down the line with different ammo because the rifle was headspacing at something extreme like .070 when the SAAMI specs have .051 as a max and many people in the target world try to achieve .043 or less in their guns.
There is also the consideration that the headspace will increase as the bolt "beds" to the new action. If we are starting off with a loose chamber and then it slacks up from there, it's literally playing with fire. Yes, it's a .22 and it's not going to sheer lugs and cause "bolt-in-forehead"- but it is a safety concern and one can readily reduce the risk.
OP- If you don't want to buy the set from Brownell's,
http://www.forsterproducts.com/catalog.asp?prodid=700650 This a field gauge, the biggest of the chamber gauges. Sometimes you can still safely fire a rifle that will close on a No go gauge, so if it closes on this I would definitely prepare myself for some bolt work. You can use a few rounds of .22 as your GO gauges, just chamber and eject them and look for deformation. Again, when I'm throwing out advice for something that concerns firearm safety, I really aim to go for the most thorough and universally accepted methods, but I know that the $60 set is steep for a set of tools you'll rarely use. It's like this AWESOME pitman arm puller I have in my garage. I think it was about 40 bucks, and it did an amazing job the
one time I had to pull the pitman arm on my truck.
Another option if you absolutely don't want to get the gauges is you can use a .22 rim thickness gauge if you have a good set of 6" calipers. You can measure the brass after firing to see how it fire formed and get a decent estimate of headspace. However, this obviously involves firing the gun without checking headspacing.
You won't need to go to a smith. If you've got a few basic tools and are somewhat handy, you'll be able to handle fitting the bolt to the gun. You can lap the recoil lug or take away material between the bolt halves to get more space or shim the halves to take space away.