If you have a stable gun rest, or better yet a gun vice, pull the breach plug and drop the action so you can sight through the barrel at a dot 15 to 25 yards away. Center the barrel on the dot, then, without bumping the gun, look through the scope and adjust till the crosshairs are lined up with the dot. Reconfirm the barrel centering and the crosshairs are both on the dot. At this point you should be on paper out to at least 50 yards.

I perfer to set my dot at about 25 yards and then line it all up as that comes closer to getting me on paper than something closer which tends to put me high at 50 yards. Another rest you can use is a cardboard box long enough to rest your gun on after cutting some notches at the top of the open top, one on each end of the box to hold the gun upright. Good luck with it.