Kinda looks like today's Tubb captive recoil lug for Remington 700s. In use, the stock would probably be as fragile as the Winchester 88s around the action area.
I guided for elk hunters for many years and I've seen several 88 stocks break. Savage 99s, with their two-piece stocks are WAY better for horse and mule work.
Uber-COOL rifle. How flippin' great to see this.
Thank you, RAS.
Steve