View Full Version : Introduction to Importance of a Secure Scope Mounting System

04-23-2012, 10:16 AM
Introduction to Importance of a Secure Scope Mounting System

The weakest link in a shooting system is your scope mount. The finest rifle and scope combination is rendered useless without rugged and reliable rings and bases. Often, a problem is not foreseen and results in a miss, or even worse, a wounded animal. Countless rounds have been wasted due to the improper installation of rings and bases, and the frustration that results from missed easy targets takes the fun out of informal plinking and target shooting.

Poor base and ring installation may result in more than bad accuracy. It can destroy scopes and damage rifle receivers and bolts, and can even be dangerous to the shooter. Having a gunsmith install these critical links between your gun and scope is always a good idea, and the peace of mind from a professional installation is well worth the small fee. Do-it-yourselfers often end up spending the saved money anyway on ammo in a fruitless and expensive effort sighting in. This aggravating process is more like work than pleasure. Remember, shooting is supposed to be an enjoyable activity.

An ideal mounting system secures your optical device to your firearm as low as comfortably possible, with the fewest parts necessary. More parts equal more chances for something to go wrong. Solid steel mounts are the strongest, but in many cases, aluminum will serve perfectly well. See through rings are notoriously weak, and points of impact change from bumps or carrying are common. With a good scope with low enough minimum magnification; your iron sights will never be used.

The following are some of the most common mounting systems.

Weaver Style

The most common scope mounting system is called a Weaver style. These utilize the flat rails with crosswise slots in them that you see on everything from rifles to shotguns to handguns. The Weaver style bases are 7/8 inch wide and accept Weaver style rings. Most manufacturers make Weaver style rings. There are crosswise protruding rails, a type of recoil lug, running underneath the rings that fit into the corresponding crosswise slots in the Weaver bases. This prevents movement fore and aft under recoil and abuse. The bases may be one or two pieces and be made of steel or aluminum. Weaver rings are detachable from their bases with the scope still in them, and can be reattached without a major loss of zero. The scope can be reinstalled on a different gun, or removed for gun maintenance or travel. Swapping scopes for different purposes is also facilitated.

Picatinny / MIL-STD-1913

Picatinny rails are similar to Weaver rails (bases), and have a standardization first published by the Picatinny arsenal in 1913. The major difference between Weaver rails and Picatinny rails are the width of the crosswise cuts in them. Picatinny bases have wider slots. The recoil lugs under picatinny rings are thicker to correspond to the wider slots in picatinny bases. Therefore, Weaver rings will fit on picatinny bases, but picatinny rings won't fit on Weaver bases. This is how it's supposed to work, but Weaver style base manufacturers have been cutting thicker slots in their bases to accommodate picatinny rings, and picatinny ring manufacturers have started to put smaller recoil lugs on their rings. The instances of an actual picatinny specification ring not fitting on any Weaver style or picatinny rail are few, and not something to be overly concerned about unless we're talking about the very best mil-spec equipment. Some Picatinny rings are tightened with a torque wrench to a certain number of inch-pounds for repeatability.

22 Rings / Tip-off Rings / 3/8" Dovetail Rings

3/8" dovetail rings are normally used on grooved receivers. Grooved receivers have cuts running lengthwise in the of the gun deep enough for the claws of the rings to firmly grip on. Grooved receivers are normally found on 22 rifles and airguns (although some European 22s and air rifles have grooves that are 11mm or 13mm). Sometimes there is actually a 3/8" base screwed onto the receiver instead of grooves cut into it, often because of lack of metal thickness of the receiver.

These 3/8" rings may have a circular diameter to hold a scope with a main tube of 30mm, one inch, 7/8", 3/4", or others. A standard 22 ring might be called a "one inch tip-off", or a "one inch 22 ring", or a "one inch 3/8" dovetail ring".

Some grooved receiver 22s are drilled and tapped for Weaver style bases. It is prudent to use these much larger bases if available. Weaver style bases simply offer more area for the rings to grab.

Redfield / Leupold Style

The Redfield / Leupold style of bases and rings are a standard that non-weaver mounting systems are measured by. They can be one or two pieces, and are steel, sleek, and strong. They are reliable and trouble free. There is almost as much interchangeability between manufacturers with these systems as there is with the Weaver style. Unlike Weaver style rings, Redfield / Leupold style rings are not detachable. The half of the rings must be separated to remove your scope.

The front ring is kind of a press fit, with a protruding, beveled rectangle of metal under the ring, turned tightly into a corresponding dovetail slot in the front base. Normally, the two halves of the ring are loosely assembled, and a scope ring tool or a one inch wooden dowel or a screwdriver handle is inserted between the pieces to gain leverage to turn the ring into the base. This can not be done by hand.

The rear ring sits flush against the base and is held there by two opposing screws tightened into it. The screws have a leading edge that fit into corresponding slots in the ring. The base screws are tightened into each other, squeezing the ring tightly and immovably. By backing out one screw and tightening the other, the ring moves laterally on the base, effectively acting as a windage adjustment. This is of minimal importance unless your base screws are tapped into your gun's receiver crooked, or there is some other problem that makes your gun shoot left or right so much that it can't be easily corrected with minor scope adjustments.

Dual Dovetails (DD) Systems

Dual dovetail bases are the same as Redfield / Leupold style, but instead of the windage screws holding the rear ring to the base, they are omitted, and instead, the rear ring is turned in, just like the front. This does not offer the extra windage adjustments that the standard bases offer, but it is hardly ever of major importance, and the trade-off of a more securely installed ring is certainly worth the trade.

Clamp-on Mounts

Clamp on mount such as made by B-Square and other manufacturers allow easy scope mounting on guns that aren't drilled and tapped for scope mounts. They do not require gunsmithing, and are easily removed without harm. Older handguns and shotguns often utilize these mounts, making it a much more useful and fun firearm that can be shot more accurately.

Ring Height (According to the 2006 Leupold Catalog)

"50mm riflescopes will almost always use HIGH rings in a given style. In certain instances, such as with extremely heave barrels or some makes of firearm, SUPER HIGH rings may be necessary."

"42-45mm riflescopes will almost always use MEDIUM rings in a given style. In certain instances, 45mm scopes may require HIGH rings."

"40mm riflescopes will almost always have enough clearance with LOW rings in a given style, though MEDIUM rings will give slightly more clearance, particularly when using a barrel with a thicker shank portion or a heavier contour."

"28-36mm riflescopes will almost always use LOW rings in a given style. Again, in certain instances of a heavy barrel or heavy shank portion of a custom barrel, MEDUIM rings may have to be used, but LOW rings will almost always suffice."

"20mm riflescopes will almost always be able to use LOW rings, but in some cases may also use SUPER LOW rings. In this instance, bolt handle clearance of the OCULAR bell will come into play more so than objective / barrel clearance and should be carefully considered."

Points To Remember

Your ring halves are supposed to have gaps between them. Don't try to make them close. Just make the gaps even.

You can easily lap your rings by putting a small amount of jeweler's rouge or Flitz on a metal bar the same diameter as your scope tube and rubbing the coated bar in your installed rings to smooth out the burrs. Be extremely careful to remove all traces of this mild abrasive, and take caution not to get any rouge on any firearm part. When you are done, you can see the shiny places where the high spots were. This gives a more secure purchase for the rings to do their job, and firmly hold the scope.

Shimming bases is easy. Cut shim stock from a steel or aluminum can slightly smaller than the size of the base, and punch holes where the screws will go. Raising a base will give elevation that does not require your scope to be too far off center, its strongest point.

The more you remove and install turn-in rings, the looser they get.

When snapping the tight fitting halves of rings over your scope, insert a dollar bill between the pieces to prevent scratching the scope. The bill is then easily removed.

Remember, your scope mount is the weakest link in your shooting system.

04-23-2012, 11:33 AM
Great info!