From the manufacturer:
All Precision Armament Scope Rails are fully machined from a billet of ultra-strength Tennalum® 7068, offering the strength of steel at a third of the weight. Billets are stress relieved and pre-ground prior to machining to deliver exceptional straightness. Manufactured to MIL-STD 1913 dimensions with all critical contact surfaces held uniform to within 0.0003″. Fully CNC chamfered along every edge for smooth, snag free handling. Features an integral recoil lug combined with elongated mounting holes for positive lug engagement and elimination of movement under heavy recoil. Unique cross section geometry is fully FEA optimized for maximum stiffness-to-weight ratio while also providing improved ejection port access. All bases have built in 20-MOA of elevation for extended range shooting. Mil-A-8625 hardcoat anodized matte black finish. Installation guide and hardware included.
We researched this product heavily and to no surprise it rises to the high standard of all Precision Armament products. Tennalum™ is a proprietary trademarked aluminum alloy originally developed specifically for ordnance applications. Its official designation is 7068-T6511 and it boasts an almost 11% increase in resistance to breakage and 14% increase in resistance to bending compared to 7075 series aluminum alloy. Simply put, this is a serious scope base for serious rifleman--be it on your .223 varmint rifle or a .338 Lapua Magnum! We put our utmost confidence in the reliability and repeatability of this scope base and it's the standard base we use for all custom rifle builds.
We offer this scope base in short or long action as well as standard 6-48 mounting screws or the more robust 8-40 mounting screws. NOTE: using 8-40 screws will require your action be modified by a qualified gunsmith machinist to accept the larger mounting screws. Some premium actions come with 8-40 threaded scope base holes. Check with the manufacturer of your action for specifics. Factory Remington 700 Short and Long action rifles are 6-48 threaded.