Like I said in Filroy's link, tilting bolt actions are the easiest actions to test head space than any action on earth Without a headspace gauge. Perfect headspace on any firearm is about .004-.007 worth of space between the in battery bolt face and face of a chambered factory cartridge. In the SKS, put the stripped bolt in battery against a factory cartridge and feeler gauge the gap between the bolt and locking shoulder. If your gun did not pass the no go gauge test, I'm guessing you have more than 8 or 9 thousandths there on feeler gauges. You could be only 2 thousandths more than a no go gauge would allow and be perfectly OK shooting the gun. The gauges are great for chambering a brand new barrel but in practicality, they are not the last word in safety. That, must be calculated as to a specific amount of headspace in the gun and cartridge being used. For instance, Black powder cartridges work on so little pressure, head space is like hand grenades, "close enough" is good enough. So a few factors can be put in place as to if a gun that fails a no go test is safe enough to fire. First is by how much space, Cartridge pressure ratings and cartridge casing design. And in the end, if the test failure is by an insignificant amount such as .004-.006 over and beyond the .007 max, a close inspection of fired cartridges will tell you alot about and approaching unsafe stress in the firing process. On this particular cartridge, you can take into account the cartridge design is pure military in that the casing features alot of strength in the head end of the cartridge, So it can handle bad head space bulging well and would more likely just split at the neck in a unsafe head space condition as well as bowing out primers or just ejecting cartridges with raised primers. Bore condition also plays into the issue. So to sum it up, feeler gauge your locking shoulder space, that will give you a hell of alot more info on the safety of your gun than a no go gauge. You can even do the test with the No Go gauge chambered up for exactly why the gauge is insufficient by exactly how much. No need to guess anything here with a tilting bolt gun.