Mounting your riflescope properly is important. If the scope is not mounted properly and secured well, shots will go all over the target and sometimes OFF the paper. A poor scope mount can also result in an injury to the shooter called "scope bite."
First, take the time to mount your bases using the proper sized bit for the job to avoid stripping the head of the screw. Some shooters advise Threadlocker or Loc Tite for the screws.
Next, clean the rings to remove all grease or oils. Secure the bottom rings to the bases. Some rifles have Picatinny rails and the lower ring mounting directly to the rails will be the first step. Check to be sure your scope will sit in the cradle of the rings and leave room for adjusting it forward and backwards, and also leave room for the power adjustment. Pull the scope back as you settle in behind the firearm so you can see the entire objective sight picture without creeping up on the scope. Leave a little room for recoil.
Orient the reticle so that the vertical crosshair is true at 12 o’clock to 6 o’clock, and the horizontal crosshair is at 180 degrees on the horizon. Some people put the gun in a vise and peer through the scope with the rifle perfectly flat and align the crosshair with a door frame, a plum bob, or line the crosshair up with another known vertical object.
If you don't have a plumb bob, a makeshift one can be made by hanging a string with a weight at the bottom from a tree limb, rafter in a house, shed or garage. Don’t use a tree trunk, as trees are not perfectly straight! Some shooters take a tiny pocket level and place it on the uncapped turret of the scope and get things square that way. Whatever you do, do it carefully!
Carefully place the top half of the rings on the scope and drop in each screw and start to snug each screw. Threadlocker or Loc Tite can be used if you desire. Do this the same way you would tighten the lug nuts on a tire. Start with one, then do the one diagonal from it, but do not fully tighten. Try to turn the screws the same amount of turns rotating your way around the screws diagonally until you get them all snug. Stop about halfway through when the scope will not move if you shoulder the firearm.
Shoulder the firearm and peer through the scope to test the eye relief. (That's just the term we use to describe the space between the scope and where your eye will be.) I make a point to put on what coat or jacket I typically wear when hunting to be sure the eye relief will be correct. If necessary, loosen the scope and slide it back a bit, then retighten. Continue the steps below.
Stop when the scope is somewhat snug. Look at the space between your upper and lower rings to ensure you have the same amount of space on all four sides (two on the front bases and two on the rear bases left and right accordingly). Continue snugging the screws to approximately 20 inch-pounds. Do not overtighten as you can damage the scope or strip the screw head.
Recheck the eye relief and work the action to be sure the scope is not mounted in such a way as to interfere with quick working of the action in the field. The next step is to test the scope and sight it in on the range!
A few last tips
Do not skimp on bases or rings. Get quality hardware. This includes screws. Most bases and rings come with screws. If you have poor quality bases or rings you will likely end up with some problems at some point.
Be SURE to use the correct size bit to tighten the screws. Invest in a decent quality gunsmith bit kit that has all the sizes in one place. Having one is a game changer and keeps shooters from stripping screws and having to drill them out!
Do not overtighten as scopes can be damaged or screw heads can be stripped or even broken if torqued too much.
Be sure to place your bases where the rings will allow the most adjustment forward and rearward for the scope to not interfere with the gun action and allow for a clear sight picture while not giving the shooter “scope bite.”
