For 10 years or so I've used a Mec [ 600jr, 650, or Grabber ] to load BP. Don't understand how you get a spark with a aluminum charge bar - anyways, I've never had a problem.
Paul,
While I'm no chicken little, I don't use the MEC presses to actually throw the BP, preferring to dip and pour it from a separate container. The issue with using the MEC to load BP, in my understanding, arises not from the possibility of a spark forming from metal to metal contact, but from static electricity that builds up in the plastic bottles used to contain the powder and shot.
I have always seen flakes of smokeless clinging to the side of the bottle because of static electricity build up, more so during winter months, but somewhat year 'round. The possibility of a partially filled bottle of BP flashing off 20" from my face just keeps me erring on the side of caution.
All my best, Stan
