Ignition is easier at room temperature and more difficult when the rifle is cold. If you are on the ragged edge of ignition to begin with, the temp change will make the difference.
if you are going to do a bare primer conversion, the Lehigh unit is a good choice. And the 2 'hottest" 209 primers are considered to be the Federal 209A and CCI 209M. I would be sure to use one or the other.
I have a box of the Fed and a box of the CCi's so I am set in that department.
Any idea on where to get the lehigh breech plug?
