Of the various Remington hulls, which ones are
the STS hulls (12 or 20 ga)?

Most of them are a dark gree with a shine to them. They clearly state on the hull Remington STS. You can also use Nitro hulls which are gold in color in the same manner as they the exact same hull.

Old Elk Hunter, and the 20's are yellow witha smooth hull and STS in black ink on the side.

Btw, do you only hunt old elk? The young ones taste better.

Customstox,

Being old and slow, I prefer to hunt old and slow game also. Since I also eat slow, the fast young
taste is gone before I am done so the old elk taste the same as the young elk. As for cows, I prefer the young and tender just like I like eating young and tender wo......