Choosing a scope
How to Choose a Riflescope
Quick answer
The order that actually matters when choosing a riflescope is fit, then reticle-to-turret unit match, then a usable exit pupil at the power you will really shoot, with glass quality last, which most buyers reverse. A well-matched all-round choice like the Vortex Diamondback 3-9x40 Riflescope, Dead-Hold BDC Reticle at $249.00 gets all four right at once.
Most shopping for a riflescope starts with the question that should come last: which one has the clearest glass? By the time that question gets asked, three earlier questions that actually decide whether the scope works on your rifle at all have usually been skipped, which is why so many scopes come back after a single mounting attempt.
The order below is not a preference. It is the order in which each check either eliminates a candidate outright or changes what the next check needs to look for. Doing them in reverse does not make the scope worse; it just means you find out about a disqualifying problem after you have already paid for shipping both ways.
What order should you actually check things in when choosing a riflescope?
- Confirm what your rifle and mounting hardware will physically accept. Before comparing a single spec sheet, know your tube diameter options (1 inch, 30mm or 34mm), what base or rail your receiver takes, and roughly how much clearance you have between the barrel and where an objective bell will sit. This single check eliminates more candidates than every other step combined.
- Match the reticle unit to the turret unit. A mil reticle needs mil turrets and an MOA reticle needs MOA turrets. Check the actual product description, not the marketing name, since two scopes that look nearly identical in a listing photo can ship with mismatched units. A reticle and a turret speaking two different languages means every hold and every dialed correction answers a different question than the one you asked.
- Decide the magnification you will actually dial to most, not the number in the ad. A 6-24x scope is sold on the 24. Most owners live somewhere between 8x and 14x in real use. Be honest about where you will actually leave the ring before the next check, because the next check depends entirely on this number.
- Compute exit pupil at that real magnification and check it against your own use case. Divide the objective diameter by the magnification you settled on above. A number under 3mm is a fair trade on a bright bench and a real handicap at dawn or dusk. See the magnification guide for the full arithmetic before you commit to an objective size.
- Only now compare glass and coatings among scopes that already passed the first three checks. Once fit, unit match and exit pupil have narrowed the field, resolution and low light performance are the real remaining differences between two otherwise-qualified candidates, and this is the point where paying more actually buys something.
- Confirm the ring height, base and torque hardware the specific scope you land on will need. Objective diameter and tube size, now both known, determine ring height. Work that out before the scope arrives rather than after, so mounting hardware shows up at the same time as the scope.
- Mount, level and zero before trusting the scope for anything. A correctly chosen scope still has to be mounted correctly to deliver on any of the checks above. Follow the mounting and levelling guides in order, and confirm the zero only with live fire on a supervised range or a safe, legal backstop.
The order most buyers use, against the order that avoids a return
Reversing this order does not usually produce a bad scope. It produces a good scope that does not fit, does not match its own turrets, or goes dim exactly when you need it most.
Fit, unit match and exit pupil eliminate or confirm a scope before glass quality is ever compared, and doing that in reverse is one of the most common reasons a scope gets returned.
Shooter convention
| Check | What it decides | What happens if you skip it |
|---|---|---|
| Physical fit (tube diameter, objective clearance over the barrel) | Whether the scope can be mounted on your rifle at all | A scope that has to go back because the objective bell will not clear the barrel or the bases will not reach |
| Reticle unit matches turret unit | Whether your holdover marks and your dial clicks agree with each other | A mil reticle under MOA turrets, or the reverse, so every hold and every dialed correction answers a different question |
| Exit pupil at your real shooting magnification | How usable the image actually is at the power you dial to in poor light | A scope that looks great on a bright bench and goes dim exactly when low light hunting needs it most |
| Glass and coatings | Resolution, contrast and how gracefully the image degrades at the margins | Rarely a return reason on its own, which is exactly why it belongs last, not first |
Fit and unit match are pass or fail. Exit pupil and glass quality are matters of degree, which is why they belong later in the decision, not earlier.
Why most buyers start with glass and end up disappointed
Glass quality is the easiest thing to compare from a listing, since it shows up in review language and marketing copy about lens coatings and edge-to-edge clarity. Fit and unit matching do not show up that way; they require reading a spec sheet against your own rifle's measurements, which is more work and less fun than reading about glass.
The result is a shopper who picks the scope with the best-reviewed glass, then discovers during mounting that the objective bell needs rings taller than anything they own, or that the reticle they liked in a review photo is a mil reticle sitting on MOA turrets. Neither problem is the scope's fault. Both are avoidable by doing the boring checks first.
Sources
- Manufacturer published tube diameter, reticle and turret specifications
- Owner-review consensus on common scope-buying and mounting-return reasons
Frequently asked questions
What is the single most common reason a scope gets returned?
A physical fit problem discovered during mounting, most often an objective bell that will not clear the barrel in the rings the buyer already owns, or a tube diameter that does not match the rings on hand. This is entirely avoidable by measuring the mounting hardware and the objective diameter before buying the scope, not after.
Does a more expensive scope always perform better on my rifle?
Not if it fails an earlier check. A scope with excellent glass but a reticle unit that does not match its own turrets, or an exit pupil that goes too small at the magnification you actually use, performs worse in practice than a cheaper scope that passes fit, unit match and exit pupil cleanly. Price only pays off once the first three checks are already satisfied.
How do I know if a reticle is MOA or mil before buying?
Read the reticle name in the actual product description rather than assuming from a photo, since the two units look similar at a glance. Manufacturers generally label it directly, such as EBR-7C MOA or a MIL designation in the reticle's own name. If the listing does not say, treat that as a reason to look elsewhere rather than guess.
Do I need a first focal plane scope for my first riflescope?
Usually not. First focal plane only matters if you plan to use holdover or ranging marks across the whole magnification range, since those marks stay correct at every power. A second focal plane scope, sold at a lower price for a similar spec sheet, is a reasonable first choice if you mainly use the center crosshair and dial corrections instead of holding over.
What magnification do most shooters actually need?
Less than the top number printed on the box. Most hunting and general-purpose shooting happens well under the maximum magnification of a variable scope, and buying based on the largest available top end usually means paying for exit pupil and field of view you will rarely use. The magnification guide on this site works through the real numbers.
Should I buy scope rings before or after choosing the scope?
After. Ring height depends on the specific objective diameter and tube size of the scope you land on, so buying rings first means guessing at numbers you do not have yet. Choose the scope, confirm its objective diameter and tube size, then size rings to match.
Researched, not professional advice. This page is compiled from published manufacturer specifications, published optical and ballistic formulas, and owner-review consensus, not hands-on testing. Figures described as a rule of thumb are shooter convention rather than sourced numbers, and they are labelled that way wherever they appear. Ballistic figures come from a point mass model using the ballistic coefficient the maker publishes, so treat them as a starting point and confirm them on paper at a measured distance. Confirm your firearm is unloaded with the action open before you mount, level, torque or bore sight anything. Verify a zero only on a supervised range or a safe, legal backstop, know what lies beyond your target, and follow the law where you hunt and shoot, including rules on land access and permitted cartridges.