DF
Considering when the rifle was assembled I bet it is a 1-10. In those days the 6 Rem had the fastest twist which was either 9.5 or 9.75.
I don’t think Douglas made anything faster than 10.
The 6mm Remington had a 1-9 twist from the get-go, since Remington wanted to get well beyond the 1-12 debacle.
In fact Remington switched to 1-9 twists in their .243 Winchester rifles at the same time, rather than have to button-rifle two different twists for the two cartridges. I know this because my first .243 Winchester was a Remington 700 BDL, purchased slightly used in 1974, which had a 1-9 twist....
