Answered this one before.
453 both screws into the action, free floating barrel
452 one screw into the action, the other screws into a block that's attached to the barrel.
I have a 453. Trigger works fine. Puts 5 shots at 50 meters into one hole the size of one .30 caliber bullet, using Eley standard(brown box)
So I take the 452 with a little trigger work would be fine for a walking rifle.
I would be getting the 17hmr version. Is there any real advantage of having the heavy barrel varmint variant over the sporter?