1. If you are a western theatre Union soldier, go with a black slouch hat over the forage cap anyway. It was infinitely more popular in the A of T.

2. If you are western theatre Union and want to go with a kepi or forage cap, either wear no hat brass at all or just go with either the regimental unit # or the Company letter on the front middle edge of the top of the cap. Or go with the Corp badge--it was used much more in the western theatre.

3. If you are eastern theatre, go with the letter or # on the front of the cap as described above, or if your original unit wore the whole gaudy arrangement of horn (cannons, etc.) and number and letter, then go with it if it is truly documented.

I believe there was indeed a significant use of some form of hat brass. The pictures I've reviewed show it. But few pictures show the loud, gaudy display of brass that some reenactors wear. It was more popular in the east than west...and was at one time ordered by Joe Hooker when he was in command of the A o P in 1863. But the key would be to document it either through pictures of men from the original unit (if possible), or by making an assumption that units from the same state or county or close geographical area tended to use similar uniforms and appearances.

In reenacting overall, a plain, march-worn, practical approach is best.