[F. Guffey]

"As virtually all rimless bottleneck cases headspacing on their shoulder are only a few thousandths inch (less than .005") shorter in their case head to shoulder reference than the chamber"

It is obvious I am not the assuming individual your are, I measure the length of the chamber first, in thousandths, I have one chamber that is .016" longer than minimum length ammo when measured from the usual places. I purchases a mill from a recourse person for anything 03 Springfield, 1911s and M1 Garands, he was making every effort get help with the length of the chamber of a Rock Island 03 period correct for 1911. He was disgusted with the big egos on the Internet, so? I informed him "This is your Lucky Day", with tools he had on the wall, on his bench and in his tools boxes I dug out enough equipment to check the length of his chamber three different ways and then gave him a choice, he had no less than 25 head space gages, none of them would give him a measurement. To shorten the story his chamber was .0075 longer than a minimum length case 'when measured from the usual places. I offered to check all of his bolts for their effect in reducing the length of the chamber. I offered to check 35+bolts I have, I also assured him how difficult it would be to find a bolt that reduced the length of the chamber .0025".

F. Guffey ++++ the Rock Island had a straight handled bolt. I have one in one of my RI and that was the only one he had.