New Hatcher hole in 1903

[ssgross]

and found insufficient head space

I need go stop posting late at night. I read the opposite of what you wrote! I've seen "short" 1903 chambers too. Sometimes there is some scale buildup or surface rust in the chamber, sometimes a burr. Sometimes it's the ammo, sometimes the chamber really is just a tad short. A light polishing of the chamber fixes the former, lightly chasing with a reamer fixes all the other. To polish a chamber, cut slot in the end of a 1/4" dowel. Fold over a small piece of 800 grit wet/dry and insert in the slot to make a flapper and spin it in the chamber. It's a good idea to mark the dowel so you don't polish beyond the shoulder.