Removing the primer pocket crimp from mil brass seems like it should be a relatively minor task, but it still needs to be done properly. Without providing the details as to the tools you used to ream the primer pocket there is no way to know where the problem lies.
Mil primer pockets can become very distorted during the crimping process, but regardless, without getting into a lot of details, you can simply use a
Primer Pocket Uniformer Tool as the final step to restore the primer pocket to the correct dimensions.
"Primer pocket uniformers are designed to ensure that primer pockets are cut to the correct SAAMI depth specifications, cleaning out built up carbon residue from previous firings and squaring the bottom of the primer pocket with respect to the case head. This step is important as variations in the seating depth of the primer can change how the firing pin strikes the primer producing inconsistent ignition. This tool features a preset stop collar set to SAAMI specifications."
