The Base Has To Fit Your Rifle — Full Stop.
You can have the best scope in the world and the best rings money can buy, but if the base doesn't properly match your rifle's receiver, none of it matters. Every rifle model has its own drilled and tapped hole pattern, and scope bases are made to match those specific patterns exactly. Use the wrong base and you'll end up with screws that miss their threads, a mount that wobbles under recoil, and a zero you can never trust. Here's how to get it right the first time.
A Properly Fitted Base Is The Foundation Every Scope Setup Depends On
Why The Right Fit Is Non-Negotiable
Older hunting rifles — and most modern ones — come from the factory with holes already drilled and tapped into the receiver. But those holes aren't universal. Remington puts them in a different position than Savage. Savage uses different thread sizes than Marlin. Browning has multiple variants of the same model with different patterns depending on year and sub-model.
Weaver and other quality manufacturers produce model-specific bases that are engineered to match those hole patterns exactly. A purpose-built base matches the receiver contours and screw hole spacing of your specific rifle, eliminating any guesswork about whether it'll line up. If you try to use a base made for a different gun, the holes won't align, the screws won't catch their threads properly, and you'll end up with a loose or incorrectly seated mount — which means a shifting zero, potential damage to the receiver, and a lot of frustration at the range.
One-Piece or Two-Piece? Know The Difference
Once you know you need a model-specific base, the next question is whether to go with a one-piece rail or a two-piece base pair. Both have legitimate uses — the right choice depends on your rifle and how you shoot.
Maximum Adjustability & Strength
One-Piece Rail
A single bar running the length of the receiver — sometimes extending toward the barrel — machined to fit your specific model. Because it's one solid piece, it's extremely rigid and gives you a long run of Picatinny slots to position rings exactly where you need them. Great for big, heavy scopes and shooters who want maximum fore-aft adjustability for eye relief.
The one caveat: on lever-actions and top-loading rifles, a full-length rail can cover the loading port and get in the way of running the action. Check your rifle's loading style before committing to a one-piece.
Lightweight & Traditional
Two-Piece Bases
Two smaller blocks — one at the front of the receiver, one at the rear — that work together as a matched set. Lighter and less bulky than a full rail, they leave the top of the action open. For rifles that use stripper clips or load from the top, two-piece bases are often the only practical option.
Many classic bolt-actions — Savage 110, Remington 700, Winchester Model 70 — use two-piece Weaver-style bases as the standard setup. You get fewer ring position options than a long rail, but for most bolt-gun hunting setups, that's more than enough.
A Correctly Fitted Base Locks Into The Receiver With Zero Slop
Stop Guessing — Use The Weaver Fit Finder
Finding the right base used to mean digging through a thick catalog, reading across rows of small print in a fit chart, and hoping you didn't miss a footnote about a model variation. Weaver's Fit Finder makes that whole process take about 30 seconds.
Select your rifle's make and model, answer a few quick questions about sub-model details, and the tool instantly recommends the correct base and rings for your specific gun — complete with part numbers, pricing, and links to buy. No guesswork, no cross-referencing, no wondering if the Savage 110 base you found on clearance actually fits your action year.
Weaver Tool
Find The Exact Base For Your Rifle In Seconds
Select your make and model. Get instant recommendations for the correct base, rings, and part numbers — matched to your exact rifle. No charts, no guessing, no wrong orders.
If you prefer to go old-school, Weaver's printed base charts are still available — find your rifle's make and model, read across to the base code, and use that part number to order. The chart is thorough and covers hundreds of rifle models, including notes on variations like action length, screw size changes, and left-handed versions. But honestly — the Fit Finder is faster and harder to misread.
How To Pick The Right Base: Step By Step
Know Your Rifle's Full Details
Model name, action type (bolt, lever, semi-auto), action length (short vs. long), and any special features like an AccuTrigger, left-hand action, or hinged floorplate. Some rifles — like the Browning A-Bolt — have multiple versions that take different bases, so the more specific you can be, the better.
Check The Fit Finder Or Base Chart
Run your rifle through Weaver's Fit Finder at weavermounts.com, or look up your model in the printed base chart. Either will give you a specific part number for the correct base. Don't skip this step — don't guess, don't assume a base "looks right."
Verify The Screw Thread Size
Some rifles changed thread patterns over their production run. A notable example: Savage switched from 6-48 to 8-40 action screws on some Axis models around 2021. The Fit Finder accounts for this, but if you're buying from a chart, double-check the year your rifle was manufactured and match the screw spec accordingly.
Order The Correct Base — Pair Or Single
Two-piece base pairs come as matched front and rear sets — you need both pieces. Some listings show "front only" and assume you already have a rear. Pay attention to what's included. One-piece rails are sold as single units.
Match Your Rings To The Base
Weaver rings are designed to clamp into Weaver-style bases and Picatinny rails. Pick the right ring diameter for your scope tube (1" or 30mm are most common) and the correct height to clear your objective bell. The Fit Finder will recommend rings alongside the base so you can order everything together.
Real-World Examples: Savage 110 & Marlin 336
Let's walk through two popular rifles to show how this plays out in practice.
Bolt-Action Example
Savage Model 110
Most Savage 110 actions use a two-piece Weaver base pair. Weaver's #48465 is the standard match — a matte-black aluminum pair with a cross-lock slot design that bolts right into the 110's receiver holes.
Important note: Savage made a thread change on some Axis models around 2021, switching from 6-48 to 8-40 action screws. If your 110 or Axis was made around or after that period, verify which screw size your receiver uses before ordering. The Fit Finder handles this automatically — but it's worth knowing if you're referencing a printed chart.
Once the base pair is installed, any standard Weaver rings drop right in and you're ready to mount glass.
Lever-Action Example
Marlin 336
The Marlin 336 — and its close relatives like the 30AS, 444, 1894, and 1895 — typically use a single one-piece top mount base. Weaver's #63B screws into the Marlin's factory-drilled holes and extends back along the receiver to give you a solid mounting surface for two rings.
Unlike a bolt-action, the Marlin's lever-action cycle doesn't require a clear top, so the one-piece base works cleanly without blocking the action. Once the #63B is down, add two Weaver rings in the tube diameter that matches your scope and you're set.
No complicated math, no modifications — the charts and the Fit Finder do the legwork and you just follow the part number.
Confidence In The Field Starts With A Mount That Fits
Before You Buy: Quick Checklist
Know Your Rifle's Full Details
Model name, action type, action length, any special features. The more specific you are, the better your fit will be.
Verify Screw Thread Size
Some rifles changed thread patterns mid-production run. Don't assume — check. The Fit Finder accounts for this automatically.
Use The Fit Finder Or Chart — Don't Guess
A part number confirmed by Weaver's own fit data has already been tested to work. One that "looks right" hasn't.
Order The Full Base Set
Two-piece bases require both front and rear pieces. Check what's included in the listing before assuming you're getting a complete set.
Match Rings To The Base And Your Scope
Weaver rings fit Weaver bases and Picatinny rails. Get the right tube diameter (1" or 30mm) and the lowest ring height that still clears your objective bell.
When In Doubt, Ask A Gunsmith
If you're unsure about anything — especially if you're working with an unusual or older rifle — a knowledgeable dealer or gunsmith can confirm fit before you commit. Better to ask than to put incorrect holes in a receiver.
"Get The Base Right And Everything Else Falls Into Place."
A model-specific base that fits your receiver perfectly is the difference between a scope setup you can trust and one you're always second-guessing. It's the foundation. Treat it that way.
Use the Fit Finder. Order the right part. Torque it down properly. Then go shoot with confidence.