Rifle Scope Mounting Set-Ups
December 20, 2019
A look at riflescope mounting setups, past and present.
The quick-detach scope mount for big game rifles is an early design, and it may have originated when Zeiss introduced its first scope of that type in 1904. That was a good thing because many hunting seasons would come and go before hunters considered newfangled telescopic sights with their fragile glass innards to be reliable, and they wanted quick and easy access to the iron sights on a rifle.
Several variations of the quick-detach mount eventually became popular in Germany and Austria, where hunters often carried the scope in its own leather case and did not attach it to the rifle until arriving in the field. This common separation of scope and rifle is why it is not uncommon so see some of those rifles wearing the mounting base while the scope and rings are missing. My 1903 Mannlicher-Schoenauer carbine in 6.5x54mm is an example.
A number of quick-detach mounts were eventually introduced by various American shops with the Echo, the Akah, the Stoeger, the Paul Jaeger and a mount from Griffin & Howe some of the more popular. All allowed a scope to be removed and reattached without the use of a tool, and most did so without loss of zero. That type of mount is available today from Talley, Warne, Burris, Weaver, GG&G, Larue Tactical, Midwest Industries, Leupold and many others.
A couple of my custom rifles in .458 Lott and .50 Alaskan have the Talley and Warne mounts. They hang tough and hold true on the hard-kickers. Another of my favorites is made by Alaska Arms LLC, which is on a Ruger 77 Magnum in .416 Rigby. The one I have utilizes the integral base in the Ruger receiver, but it is also available for rifles with drilled-and-tapped receivers. The levers are located on the left side for right-handed rifles and on the right side for left-handed rifles.
Convenient access to open sights is not the only benefit to a quick-detach mount. Sometimes when I’m on an extended hunt in remote country I carry a spare, pre-zeroed scope wearing rings that match those on my rifle.
Having an extra scope on hand has paid off, with the most recent occasion being a hunt for moose and black bear in Alaska. It rained hard just about every day, and on our second day out, internal fogging rendered the scope on my .35 Whelen useless. While I could have gotten by with the very good open sights on that rifle, a spare scope retrieved from my duffle in camp increased my confidence level when the one and only shot at an outstanding bruin was quite some distance away.
Through the years other designs have offered quick access to open sights. As its name indicated, the Pivot Mount made by Weaver had a hinge that allowed the scope to be swung over to the side. It has been discontinued, but I still see quite a few in their original packaging for sale at gun shows and on the internet.
The Lo-Swing mount from Pachmayr worked the same way. A .300 H&H on a modified 1917 Enfield action I bought many years ago wore one, and in addition to swinging over to the side, it also allowed the scope to be removed from the rifle without a tool.
During the 1920s John Redfield introduced a revolutionary scope mount described by him as a rotary-dovetail design. With both rings on a scope and the scope positioned at 90 degrees from the rifle, a male dovetail on the bottom of the front ring is inserted into a female dovetail at the front of the base.
Swinging the scope in alignment with the action of the rifle solidly binds the mating surfaces of the two dovetails. The flat bottom of the rear ring rests atop the rear base and is held in place by opposing screws, the hollow heads of which engage circular grooves at the bottom of the ring. Windage adjustment can be made by loosening one screw and tightening the other.
Windage adjustment in a mount was especially important in those days because most scopes were internally adjustable for elevation only. Even when a scope had windage adjustment, it was common for enough misalignment to exist between the receiver and barrel of a rifle for its owner to use up all the adjustment in the scope before zero was reached. That did not matter with open sights because both were attached to the barrel, but it certainly mattered with a scope mounted on the receiver.
With the windage of a scope adjusted to dead center, the opposing screws at the rear of the Redfield mount (and the same design from other companies) are used to pivot the scope close to zero, and the adjustment in the scope is then used only for fine-tuning.
Making sure the screws of the front ring stay tight is important because if they become loose the scope will slide forward during recoil, causing the rear ring to gradually creep through its retention screws. The front ring pulls most of the load while the rear ring’s primary job is to keep the scope in proper alignment.
The Conetrol mount introduced by the late George Miller in 1964 is an improvement on the rotary-dovetail design because it has windage adjustment, and yet when the four opposing “cone” screws are tightened, both rings resist recoil equally. The “Projectionless” design makes that mount the sleekest and most handsome to come down the pike. I have them on several rifles ranging in recoil up to .416 Rem. Mag. and have never had one fail or lose zero. George’s brother, Don, now runs the company.
Today’s makers of telescopic sights seem to be racing to see who can make scopes with the shortest main tubes. Some are too stubby to use with most scope mounts on long actions such as the Remington 700 and Winchester 70. Extension rings will sometimes make them work, but I consider the Weaver one-piece extended base and the Picatinny-style base available from Talley and others to be better solutions to the problem.
The two types of bases look the same, but a close examination reveals differences. Cross-slots in the Picatinny are 0.206-inch wide with a center-to-center spacing of 0.394 inch. Both dimensions are consistent.
Slot width in the Weaver base is 0.180 inch, and slot spacing distance can vary. Weaver rings usually work on a Picatinny base, but not the other way around. Regardless of which system is used, keep in mind that there is often a bit of play between the recoil shoulders of the rings and the cross-slot shoulders in the base, and the scope should be pushed fully forward prior to locking the rings in place.
Many years ago I read a magazine article predicting that aftermarket scope mounts would eventually be made obsolete when the entire mount became an integral part of the rifle. The Steyr AUG accomplished this during the 1970s, but as far as I know, the feature has not appeared on a mass-produced sporting rifle.
During the late 1940s, Sako took hunters halfway there by making the scope mount base an integral part of the receiver. I still shoot varmints with 1950s-vintage Sako L46 rifles in .218 Bee and .222 Rem. and have always liked the absence of a base with screws that are impossible to check for tightness without removing the scope. The rings on another Sako in 9.3x62 I have shot a lot have never budged. It is a rugged and trouble-free design and capable of resisting the punishment of hard-recoiling cartridges.
Some years back, Sako took what was originally simple rings and made them much more complicated (and more expensive) than they needed to be. I have also tried those on a couple of rifles, and they held steady when subjected to the recoil of the .338 Lapua and the .458 Win. Mag.
All things considered, the scope mount system introduced by Ruger on its Model 77 rifle back in 1968 is hard to beat, and it is my favorite integral-base design. A round-top Model 77 with its receiver drilled and tapped for scope mounting was also introduced, but it did not sell as well and was eventually discontinued.
All screws in the Ruger mount are easily accessed for tightness checks, and the mount returns a scope quite close to zero when it is removed and reinstalled. A 25-cent piece is a good fit for the slots in the attachment screws.
I’ve lost count of the number of Ruger rifles and handguns I have hunted with through the years and have yet to experience the first problem with the company’s scope mounting system. As an added bonus, a pair of rings departs the factory with Ruger firearms designed to use them.
For those who wish to go the custom route, Briley Gunsmithing will mill grooves in the receiver ring and bridge of some actions for the acceptance of rings with its bottoms precision-dovetailed to fit the receiver. The system has only four screws, and they hold the tops of the rings to the bottoms. My Remington Model Seven FS in 7mm-08 has the Briley treatment, and neither rings nor scope has budged during decades of saddle scabbard carry and plenty of hard knocks in the field.
When installing a scope on a bolt-action rifle to be used for hunting potentially dangerous game, I prefer a two-piece base over a one-piece design because of better access to the ejection port should the need arise for single loading cartridges directly into the chamber. I have used them from many different manufacturers through the years, and while most worked just fine, my favorites are those made by Weaver, Talley, Warne and Conetrol.
Keep a sharp eye out for subtle dimensional changes. For example, when the Remington 700 was introduced in 1962, the top of the receiver ring was 0.117 inch higher than the top of the receiver bridge. The difference was reduced to 0.100 inch in 1974. When attaching one of today’s scope mounts to an early Model 700, placing a 0.017-inch shim between the bottom of the base at the rear and the top of the receiver bridge will prevent stressing the tube of the scope.
Have you ever noticed a baseball pitcher pick up a small bag from the mound and shake it in his hand? The bag contains powdered pine rosin, and a light coating on his fingers will increase his grip on the ball. Scopes with an extremely slick exterior finish can have a tendency creep forward in the rings when subjected to heavy recoil, even when all screws are as tight as possible. Coating the inside of rings with powdered rosin will prevent that. Your local sporting goods store will likely have it, but if not, an internet search will turn up several sources.
Most rings today have Torx screws, and while using a torque wrench to snug them up is not a bad idea, gripping the small wrench that comes with them at its short end when turning screws gets them tight enough while preventing over-tightening.
Some scope manufacturers say yes to liquid thread lock on screw threads while others say no. I think it comes down to how much shock the rifle will be subjected to. If my rifle will be bouncing around in the rack of a safari car for several days, its screw threads will be coated with Loctite 222. The same goes for a varmint or target rifle that will be fed many rounds each day for days on end. Semiautomatics in general and the AR-15 in particular are great at jarring screws loose.
Then we have lapping rings with tools available from Sinclair International and Wheeler Engineering. If the interior finish is rough (rarely seen in today’s top-quality rings) or if the steel bar and a coat of machinist blue layout dye indicate misalignment between the two rings, I take care of those issues with a combination of elbow grease and 220-grit silicon carbide lapping compound applied to the bar. Just don’t get carried away and overdo a good thing.