Re: upgrade questions ???
Hey there Capy. I too have a 300 RUM Sendero. Probably the first upgrade I would suggest is a good brake. The Senderos weight makes the recoil somewhat tolerable but it will be way more fun to shoot with a break.
I am told that putting in a Jewell trigger is like going from a cavalier to a cadillac it will be more adjustable and smoother therefre helping your shooting form by not having to "pull" on the trigger so hard.
Ttopper off with some good bases and ring like Nightforce, Badger or Near, and some good optics and your good to go.
I have learned and do learn a ton from this site. Happy shooting.