Fire one round and adjust sites to that impact
Have you tried their web site?
CMP, they have a web site that explains how to go about it.
No known web site.
No way to answer without the serail number.
Go to Remington's web site and request a manaual
Ruger has sn information on their web site.
Go to this site for informationhome.comcast.net/~jimringbauer/HamiltonRiflesindex.html
Compare to others at a gun show, auction site, etc..
Go to Remington's web site. They have a list of repair centers.
Contact Bushnell
You can request a owner's manual for free at Remington's web site.
Many estate and auction sites are out there. You have to check them periodically