I thoughts:
1. Epoxy would be the best holding, But it will allow slippage until it sets.
2. Thick CA, but it too will allow slippage until it sets
3. Hot Melt allows quick holding power, but unless proficient you will get "strings."
4. Small Dots of epoxy PUTTY on the back of each cartridge. There are some slow setting. And you can get Black epoxy putty. I would suggest black as it would be less noticeable than white. Epoxy putty will allow quick adhesion and still movable if position correction is needed within a few minutes span.
Do an Amazon search for Black epoxy putty and several come up.
If you want gold colored you can get gold colored Bondo, which will appear the same color as the brass, but make small amounts as it begins to set in 2 minutes.