What twist? Looks like a custom barrel.
Some back in the day were 16 twist.
They were pretty much all 16" twists, which is fine for 45gr and lighter Hornet bullets. Faster twists and heavy bullets are kind of counter productive in a Hornet - it'll never be a "long range kill 'em out at the periphery of your vision" cartridge. One of my four Hornets has a fast twist, 1-9" (a European gun), and it handles 60's like nobody's business accuracy-wise, but those heavy bullets with their thicker jackets made for much higher velocity don't expand worth a crap at Hornet velocities. Sure, the range is extended somewhat but then bullet drop compensation raises its ugly head and wind has a more deleterious effect because they're only loafing along. Use a Hornet like it's intended and life is good.
I swear, Kirk, I'm gonna pack the trunk full of Hornet rifles and drive to Montana some day for a taste of those little varmints!