The answer from Trijicon
Sorry for the delay in the response.
In answer to your question about the TA21 mounting on you Winchester 70 375HH with Talley rings.
You may need to have a offset ring to mount that to your rifle. With a longer action rifle the distance between the scope rings may be greater than the space available on the Scope, due to the front bell of the scope.
This is why we came out with the TR24 1-4X24 w/ 30mm tube.
Un like the TR21, the TR24 is a straight tube. This allows the scope rings to be mounted at any distance available.
TR21G
TR24G