Choose the correct bases that fit your rifle or shotgun.

• They must fit your exact model. X-Bolts, AB3s, BARS, etc. . . . they all take different bases.
• They must be the kind of base you want to use. Not all bases are separate from the rings -- two-piece bases are the most common, but integrated bases with rings included as part of the base are very popular.
• Choose from a) Browning-Style base, b) Weavers-style, and, c) Weaver-style rails.
• Choose wisely: the base you choose will commit you to the type of ring. You can't mix a "Browning-Style" base with Weaver rings, for example. 
• Rails must be an EXACT fit to your rifle or shotgun. No leeway at all. 

Rings must be made to fit the design of the bases you chose. Now that you have chosen a base style . . . 

• Choose from ring styles that match the style of your base (you don't have to do this if you buy integrated bases and rings}. 
• Choose the correct ring diameter to match your scope. Usually 1 inch or 30mm. You must match the exact diameter for your scope. Period.
• Choose the finish or color you desire. This is simply your choice. 
• Choose the height that will allow your scope to mount without the front objective bell touching your rifle or shotgun barrel. Scope objectives vary widely. Use the guide below to prevent making a mistake. If in doubt, choose high rings. most modern scopes have larger objectives than in the past. Up to 56 mm and more. Check on your scope.
• Make sure you have the proper clearance for your bolt and for cartridges to eject. If in doubt, go higher. 

The right rings. One of the most common questions asked to our customer service department is "how do I determine which bases, rings, and rails are appropriate for my rifle?" This also applies to scoped shotguns, in some cases. The answer is often difficult and a bit complex for several reasons.

• Several types of bases and rings are offered for Browning rifles, such as 1) integrated, 2) separate bases and rings, and 3) Weaver-style rings that mount on a rail base, among others.
• Scopes are sold with objectives (front bell) that vary in diameter all the way up to a 56mm objective. Historically, hunting objectives were so small that they rarely created a problem. 
• Scopes vary in length which can result in the objective being closer to the chamber portion of the barrel (which is a larger diameter).
• Adjusting for eye relief can affect where the objective sits in relation to the barrel. 
• Sloped or canted rails are available (usually 20MOA) that allow a scope to function at longer ranges (generally 600 yards and beyond). This also can result in moving the objective closer to the barrel. 20 MOA rails generally require scopes with 30mm or 34 mm tubes.  
• Barrels vary in diameter. A target barrel can be significantly larger in diameter than a sporter barrel, which, in effect, closes the gap between the barrel and the objective.

X-Bolt with 20 MOA rail. The clearance between the scope objective and barrel is excellent. 

There are two main reasons for using a rail.
    1) Ease of mounting using the Picatinny Rail system and appropriate rings.
    2) Sloping the base (usually by 20 MOA) to allow for shooting effectively when dialing in with an MOA-type scope at extreme ranges. 

Choosing a rail. It is EXTREMELY important that you order the correct length of rail for your Browning rifle. Rails generally come in four lengths.

• Magnum Action
• Long Action 
• Short Action
• Super Short Action

You generally can choose from two types:

• 20 MOA (sloped for extreme long-distance shooting)
• Standard (flat top surface, with respect to the bore.)

IMPORTANT: Browning X-Bolt rifles chambered in 300 RUM and 375 H&H require the "Magnum Action" X-Bolt rail. 

What is a 20 MOA rail?  A rail is a one-piece base that when attached to your receiver is angling down toward the barrel's bore centerline. The most common slopes at 20 Minutes of Angle. That is approximately .33 degrees. What is the benefit of an angled rail?

• When a scope is mounted it initially is zeroed to a target usually at 100 to 200 yards.
• You only need a sloped rail if you will be dialing your scope for longer ranges. Longer ranges are usually 500 or 600 yards and beyond.
• With many scopes at longer ranges, you run out of crosshair vertical adjustment beyond 600 yards.
• To solve this, you can use a 20 MOA rail which, after zeroing, leaves extra adjustment for dialing in at very long ranges. 

If you don't have a scope made for dialing in longer ranges and if you don't usually shoot beyond 500 or 600 yards, you don't really need a slanted rail. 

20 MOA is not a lot, but it can move a tight scope objective too close to the barrel, causing it to touch. To be safe, order the next higher rings when using a 20 MOA rail, especially with a target or semi-target barrel. 

Importantly, if you are using a scope with a ballistic compensating reticle, you probably don't need or want a 20MOA rail. 

There are a few easy things to always do when attaching a rail to your Browning rifle:

• Before you start insert all the screws in the holes on the rail.
• Place the rail on the receiver and line up the holes without turning in the screws.
• Once lined up, finger tighten a screw a couple of threads. 
• Continue front to back to front to back, or in a figure eight pattern (on X-Bolts), hand screwing, until the base is attached with all screws loose.
• Carefully tighten each screw until finger tight.
• Make sure you have achieved sufficient screw engagement of around three or more threads.
• Using an inch-pound torque wrench, torque to the correct specification provided with the rail. 

TORQUING THE SCREWS. For X-Bolt rifles, the torque specification for attaching a rail should not exceed 18-inch-pounds.

IMPORTANT: Inch pounds are not to be confused with foot-pounds. 12 inch-pounds is the equivalent of one foot-pound. It is advisable to use a quality inch-pound torque wrench when torquing rail screws. Never over-tighten.