I?ve used A-Zoom snap caps for years in several of my pistols, but have never really thought about using snap caps in my shotguns. I have noticed the A-Zoom?s seem to wear over time, and hopefully don?t leave micro aluminum shavings behind, which they probably do. After watching several videos on these, as always there?s no shortage of complaints about every brand. Any thoughts on well made 12 gauge snap caps would be great

Old school might be to make one out of a good shell... painted orange
weighted with the lead, no powder of course, and a rubber eraser tip in primer hole.

I don't like the aluminum ones either !

I usually use some spent casings that are odd that I can?t reload that have heavy ribbing so when you paint then orange, the paint doesn?t wear off down inside the ribs of the plastic hull.
  For weight, I used old spent shotgun primers and some small and large rifle/pistol primers to fill in the gaps and then use the wife?s hot glue gun to fill in the primer area and lock all the spent primers in place.  Apply the proper crimp and lock the crimp in place with a dab of hot glue again.

WARNING:  most of the paint will wear off!!  Except inside the ribbing of the plastic.  It?s your responsibility to train safely!   All live ammo in another room can?t be stressed enough.
This is the only way around the aluminum shavings of the zoom caps that I have found.  The hot glue where the old primer would be seated acts as a buffer for the firing pin and can be repaired when/if needed with more hot glue.  Trim off excess with a razor blade.

This works for me for many many hours of defensive shotgun training in my living room and the brass heads and plastic hulls show no signs of wear and no shavings!

Hope this helps,
Steve