Re: Once fired brass and never fired brass???
Probably not at 100 yds. When brass is fired, it expands to fit the barrel's chamber; it can't go any further. Each chamber is different. For that reason, you need to full length size brass fired in another rifle, and occasionally in your own firearm. Follow the die manufacturer's instructions to set up your die. After sizing one case, try to fit it in your rifle without a bullet. It should chamber up smoothly. If not, the dimensions are still too large for your barrel chamber. Turn the sizer die down about 1/8th turn and try again. Do this until it will fit. Be sure to lube the case liberally in and out.
Beware of buyilng "once fired brass" from an unknown seller. Some of this brass has been reloaded so many times that it might disintegrate in the press.