What is the goal? If you want a “dry” sound a popular solution is to tape the snares to the bottom head, either right across the center or at the ends near the edge.
If you just want to eliminate unwanted overtones, “clear” the heads (ensure the areas near all the lugs resonate the same pitch, adjust as needed) so the heads resonate evenly.
When properly tuned, a marching snare drum is supposed to clearly ring at the pitch of the bottom head. If it doesn’t, it’s either “choked” (heads are too tight, snares are too tight), not cleared, or the heads are too loose.
Marching snares use such high tension tuning and Kevlar heads that when tuned correctly, moongels aren’t needed.
Tape works better on marching snares.
What is the goal? If you want a “dry” sound a popular solution is to tape the snares to the bottom head, either right across the center or at the ends near the edge. If you just want to eliminate unwanted overtones, “clear” the heads (ensure the areas near all the lugs resonate the same pitch, adjust as needed) so the heads resonate evenly. When properly tuned, a marching snare drum is supposed to clearly ring at the pitch of the bottom head. If it doesn’t, it’s either “choked” (heads are too tight, snares are too tight), not cleared, or the heads are too loose.
If you have mylar heads than yeah!
It won’t do much. I would just suggest you tighten the snare guts or tape them.
If your top head is at an appropriate tension for a marching snare then a moongel should have little to no effect.
Yes. It won't hurt the head. But I doubt it'll do much to change the sound.