You've just purchased the most rugged & durable scope available. I believe 458Win himself swears by these scopes. I've got one on a Ruger M77RLS carbine & at 7.5oz., it perfectly balances the rifle. If I'm not mistaken, the compacts were made in the 1980's & 90's, then became the FXII Ultralights. The parallax I'll guess is 100yds.
