Chuck Schwartz, Z mark

Good morning,
I know there is a thread for Chuck’s work and I do think this is by him but thought I would confirm as the mark on BISPM is more like the tick / squiggle that studio describes and the mark in the book shows an incised ‘Z’ as this one has but it’s not as ‘rigid’ for want of a better word.
I’m pretty sure it is though interested what others think and I did buy it at auction as being by Chuck.

Marks book said he used a Z. The example on BISPM is his other mark, CS. Most of his work is unmarked. Which auction house sold it? I'd trust the attributions of Partridges and Maak

Yes it’ was Jason at AP’s
I put it on eBay this morning - it sold within 15 mins!

Probably right, then. He usually asks on FB if he’s unsure. And plenty of experienced collectors at the auction who would put him right if it slipped through