Sometimes 8x57 IR/IRS cases are made from 444 Marlin, but 444 cases can cause inconvenience because it is simi-rimmed rather than rimmed and may sometimes get behind the extractor. A drilling extractor engages the "top" of the case and gravity works to move the case away from it. Tolerances in chambers sometimes allow the rim to fall behind the extractor, causing barrels to fail to close. This is not likely to be a safety issue, but if you have a deer on the ground trying to get up and the gun won't close, it may take a while to remember why. I use 444 cases for 410 carpenter bee loads in a single shot pistol, and the rims often get behind the extractor. When the quarry is a carpenter bee, it is not important, though.
Mike
