Laminated Beech I believe. I know early and mid 30s had walnut but switched to laminates.
Yup....Beech is one of the most common war-era woods.
"Much that once was, is lost. For none now live who remember it."
On K98's solid wood 'till '39 (and also later, but rarely and randomly); then laminate (red glue 'till the end of the war, but in the last month white glue stocks were also used).
The first G41's were issued with solid wood, then ('42 circa) switched to laminate too.