If you’re looking for a quick answer, here it is: assuming you already have the picatinny rail in place, you need to make sure your scope mount is compatible with a picatinny rail, then slide or clasp them on. There may be screws that need to be tightened down. Don’t overtighten (a torque driver or torque wrench is your friend here), and use blue loctite if you have it.
Once the mount or rings are in place, put the scope into the rings and add the top halves if that’s the kind of mount you have. If you’re working with a red dot or prism scope, there will be some differences.
If you’d like a complete guide with more detailed instructions on how to install and make adjustments, read on!
Mounting A Rifle Scope On A Picatinny Rail
There are a lot of different varieties of mounts, rails, and scopes that make it difficult to go over one set of simple instructions on the mounting process. No matter what mounting system you have, though, you’ll want to make sure the rail is securely mounted to the rifle, then attach the bottom half of the rings or mount to the rail, then place the scope in the rings and tighten the top halves down.
Most scopes have two rings that allow you to adjust the position of the scope while you install it.
Step 1 - Confirm Compatibility
You may not actually have a picatinny rail. It may be a weaver rail, or some other type of mounting hardware. Even if you do have a picatinny rail, you need to double-check that the scope rings or mount can install on picatinny. The last thing you’ll want to verify is that the scope is going to fit on your rig with the rings you have.
You need to make sure you got the correct ring size for your scope (usually either 1-inch or 30mm). In addition, if you have a large objective lens on your scope, you need to make sure the rig is tall enough to keep the bell from touching or resting on the barrel of the rifle.
Step 2 - Mount rings or stand
Traditionally, the main way that each scope ring or stands attached to a picatinny rail was via a tightening screw on the base. This is still the case for most scope mounts, but the Quick Detach scope mount is getting more and more popular, especially for low-recoil calibers like .223. QD mounts are pretty straightforward, so let’s talk more about the tightening screw version.
As you can see in the picture, one side of the ring goes in and out as you adjust. You’ll want to position these rings on the rail at a distance that allows the scope to rest comfortably before the taper starts, like this:
Generally speaking, you want the rings to be as far apart as possible while not touching the taper and putting the scope in the right place for its eye relief to be comfortable. Be careful not to overtighten, as stripping them will ruin your hardware. For best results, use a torque driver or torque wrench and make each adjustment to these bases to between 25-40 pounds.
You can use the scope as a reference to help you position the rings, but you’ll want to get it out of the way before you start tightening.You can also use blue loctite if you know the scope is going to be on this rail on this rifle there long-term.
Step 3 - Put Scope In Scope Rings
Once the rings are mounted onto the rail, the next step is to mount the scope onto the rings. The rings should come apart with a top half and a bottom half. Remove the top half (if you haven’t already), and place the scope in the bottom halves of the rings. Look through the scope while the rifle is pointed straight forward and not leaning to either side and twist the scope until the reticle lines are straight.
Now put the top halves of the scope rings on and begin tightening. Check the scope a couple times as you make adjustments to keep the scope level. Tighten to between 15-18 pounds with the torque driver and feel free to use blue loctite if you’d like. A gun stabilizer or gun vice is handy here, but if you’re only doing this once or twice it may not be worth the investment.
Last, quickly check that you have sufficient ejection port relief so that spent brass can eject properly. Congrats, you’re done. Not nearly as complicated as it seems, but there are some little things to be aware of that can make the difference.
What is a Picatinny Rail?
A picatinny rail is a common method of attaching accessories to firearms.
What Equipment Do I Need?
You’ll need a screwdriver (preferably a torque driver) that matches the hardware your mount came with. You may also want blue loctite. You’ll also, of course, need your rifle, scope, and mounting hardware.
A leveling kit for your rifle can also help you mount a scope, but it’s a tool that is just nice to have.
How To Mount A Rifle Scope On A Picatinny Rail Base With Scope Rings
Put the bottom halves of the rings on first, making sure to position them so they’re as wide as they can be without touching the scope taper or throwing off your eye relief. Put the scope in and adjust the top half of the rings.
There are different schools of thought around mounting your own scopes to your rifles. A lot of experienced shooters prefer to take their guns to a gun shop and have them do it.
In my experience, if you’re long range shooting at distances in excess of 300 yards, working with an expensive scope (more than $1,000), or putting it on a large bore rifle, then it may be good to seek out a pro. Rifle recoils are the worst enemy of your scope, and if you don’t attach things to the rail of your rifle and adjust them to the correct point, recoil can break your scope.
Otherwise, as long as you do it right the difference will be so minute as to not be noticeable. If you need a bit more help, here’s a great video on it.