Sorry, I'm still having my doubts. I talked to a Gretsch rep at Pro Drum ..... and another at the NAMM show .... and neither would commit to saying the USA shell was maple/gum. Seems like that wouldn't be too much to ask of them. Gretsch also uses the word "formula" when describing the Catalina shell.
This, from the Gretsch web site.
"The new Catalina Maple series starts with the Gretsch maple formula shell. We carefully developed the maple shell specification to produce tones that explode with attack and volume and project a balanced amount of warm, low-end frequencies. All Catalina Maple shells are 7-ply ....."
Now, seems to me like the term "formula" is being thrown around a little too loosely, to be definitive.
Then there's articles like this......
"While there are similarities between the new Brooklyn series and Gretsch’s flagship USA Custom line, there are important differences, too. Instead of the USA Custom’s 100 percent maple shell, the Brooklyn drums have a 6-ply maple/poplar hybrid shell that’s designed to be punchy yet warm. The tom and snare shells are 0.22" thick and the bass drum shells are 0.31" thick. Both lines have Gretsch’s classic 30 degree bearing edges and Sliver Sealer applied to the shell interiors and come with “straight” shells (sans reinforcement rings)."
Not that it matters, much. I own a Round Badge kit. No need to buy a new kit.