Q. I am attempting to neck up the Winchester Super Short Magnum from .243 to .262 (6.5 mm). The cartridge is first outside neck-turned to a wall thickness of 0.012". Following some forming operations, the brass is placed in a full-length sizing die. When the 0.262" expander plug is driven down, one of two things happens: The expander plug is driven back up into the neck of the full-length sizing die or, the expander plug collapses the case neck. How can I get the case necks to expand to 0.262"?
A. The difference in diameter you are attempting to expand is not significant, and should not be offering you this much difficulty. I suspect that the problem narrows down to two possibilities—the brass is soft and/or there is not sufficient taper to your expander ball. I would bet on the latter.
Many expanders are fabricated with no taper on the bottom, the assumption being that none is necessary as they only have to pass through a fired case. You need to obtain a plug intended for neck expansion, or modify your existing one by grinding a generous taper on it. I would also recommend that you lube the inside of the neck prior to attempting any expansion. Powered graphite or mica both work well for this purpose and don’t introduce any contaminants into the powder space.
This “Questions & Answers” was featured in the January 2005 issue of American Rifleman. At time of publication, "Questions & Answers" was compiled by Staff, Ballistics Editor William C. Davis, Jr., and Contributing Editors: David Andrews, Hugh C. Birnbaum, Bruce N. Canfield, O. Reid Coffield, Charles Q. Cutshaw, Charles M. Fagg, Angus Laidlaw, Evan P. Marshall, Charles E. Petty, Robert B. Pomeranz, O.D., Jon R. Sundra, Jim Supica, A.W.F. Taylerson, John M. Taylor and John Treakle.
To subscribe to the magazine, visit NRA membership page here and select American Rifleman as your member magazine.
