The scope base is the rifles optic mounting platform.
There are 2 main types of Scope Bases:
The two-piece is where a front base and a rear base are mounted separately to the receiver.
The two-piece allows for some irregularity in the receiver manufacture and is usually lighter in overall weight. If there is any irregularity in the receiver fit, this will have to be corrected by lapping the rings when mounting the scope.
The one-piece base is just that, one piece of steel or aluminum. The one-piece is usually heavier but offers more rigidity with more fore and aft adjustment options for scope positioning. It is imperative that the fit of the one-piece base is perfect to the receiver. If not, the receiver may be distorted when the base is tightened down.
The best bases are machined from solid billet. Quite often, cheap bases warp during the heat treating process. Some cheap bases are stamped or cast out of soft steel. YOU GET WHAT YOU PAY FOR! Do not save money when selecting the mounting base. Buy the best you can afford.
There has always been much argument as to which type of base is better. One thing that can’t be argued over is the fact that you spent alot of money for an expensive rifle and scope. That makes buying cheap bases and rings just plain stupid. If the fit of the base to the receiver is not correct, STOP and find out why, or take the rifle to a qualified gunsmith. Bases that do not fit correctly will either distort the receiver when tightened or will work lose while shooting the firearm.
Some bases have built in recoil lugs. This is a good idea that allows greater rigidity of the base under the recoil of the rifle. Good quality bases also have high quality mounting screws.
Common American sniper scope bases are built to the Military Picatinny 1913 Standard.
Some bases have a 20 MOA or more angle built into the base so that the scope is mounted with a down angle relative to the bore of the rifle. This helps with the range of adjustment available in the elevation turret of the scope.
Some of the good quality bases we have used are manufactured by Leopold, and Badger Ordinance.
The rings mount the scope to the base.
There are also many different types of rings available.
The quick detach style scope rings do not have a place on a sniper type rifle. Your rifles zero may save your life or the life of someone else. Are you prepared to gamble? I’m sure not.
We prefer the Leupold MK4 Tactical scope rings.
Quality 2 piece rings with at least 4 screws each are required. Some rings have 6 screws on each ring.
One thing to bear in mind is that the wider the ring the more the probability of tweaking the scope body when tightening the ring halves if the rings are not perfectly aligned.
Rings should always be selected to allow the scope to sit as low as possible on the action. You only need clearance for the objective lens of the scope. Mounting the scope higher than necessary will only cause problems with cheek weld and also make the scope more prone to damage.
Don’t skimp on rings and bases it will cause you nothing but frustration, lost time and wasted ammo.