I had to appear before my gun board (Allegan county) over a previous arrest. I'd done my probation and the charge was cleared from my record, as part of the plea agreement. The charge was not enough to bar me from obtaining a CPL, even though it was classified as a weapon related misdemeanor (possession of a switchblade).
In my case, they had the information on record, and could clearly see the charge was cleared. They asked about the particulars of the case, I answered honestly, and they handed me my CPL on the spot rather than mail it to me.
I'm not sure how Macomb county does things. I've heard they are not very lenient and take a lot of time and have a lot of delays.
A Juvenile record, depending on the charge, will most likely not be enough to deny your CPL. Generally speaking, and based on my own personal experience, you shouldn't have a problem. Can't say for certain, though, because odds are they will see the charges on your juvie record. So depending on what those charges were, despite the cleared convictions and probation, a gun board may deny, but there is a list of charges that will bar you from getting a CPL. Have to find it, pretty sure its somewhere in the depths of the MSP website. I've seen it before. Check there first if you are concerned. Or make an appointment to be at your next gun board meeting and ask them directly before you put in the application. It's a public hearing and they shouldn't deny you an audience. If your application is already in the works, and you are requested to appear, just be honest. Don't lie because they already know what you did.
