Whats the concensus for shooting with variable scope when setting the magnification, do you acutal range through the magnification settings or is it alwats at the highest?

I found myself trying to sight in my 3-18x yesterday- shooting exclusively prone It took me a while to sight in, but I was trying to  kill time  

That said, at 200 yards, I was exclusively on 18x until I thought about it and dropped to 12 x just because.
What would dictate floating the magnification setting when not shooting a 1-6

a second focal plane optic will have crosshairs that do not change in size, and these will typically be used to range at the highest optical zoom.

A first focal plane optic will range at any magnfication as the crosshairs grow and shrink as you move up and down the magnification range. They stay consistent in size relative to the target.

I wonder this too.  I am new so I have no good advice, but I have been shooting at 100 yards at my highest setting.  People have told me that you don't need high magnification for long distances but I am not sure I believe them.

Ok, experience and opinion from a competitive rifle shooter here. Take it for what it's worth which is just my opinion and observation:

Chasing magnification is generally considered ill advised but as with all things, there's a time and a place. As magnification increases the field of view shrinks and you lose situational awareness. In hunting this can mean too much mag will let you see that acceptable buck you spotted and get a bead on the boiler room but you might not see the monster trophy buck next to it or notice something else in the direction of fire that might dictate not taking the shot. Apart from the awareness issue is magnification increases the perceived shake and wobble in a shot and makes it harder to process the data coming into your eye which frequently makes the shot take longer. People have a tendency to shoot for a good hit with low power (because target:crosshair size relationships sorta limit how precisely you can place a shot) and a precise spot with high power. The longer a shot takes the more likely you are to miss, especially from less than optimal positions.

To continue (bloody 2000 character limit):

When I shoot in metallic silhouette competition most competitors (myself included) use insanely high mag optics. I use a 36x fixed power on my .22lr match gun which is used from 25m to 100m. On my high power silhouette rifles which are used from 200-500m I use a 24x fixed power on one and a 16x on the other. We're standing up unsupported in these matches so such high magnification takes some getting used to and makes things like shooting the wrong target vastly more common events than in some other disciplines. When I shoot precision rifle matches (tactical rifle pretend sniper kind of stuff) I use 10x fixed and 16x fixed power. When I'm proned out taking a 300-1000m shot on a 2MOA target I don't need 25x to do it and I don't need the extra reticle shake that comes with it. The target is big enough to get a crosshair on without completely covering it up. When I'm standing up doing silhouette shooting, having enough magnification that I can ONLY see the target I'm working on actually helps in an odd way. When I'm at the bench getting a zero or shooting for 100m groups then I tend to use the maximum magnification that I can before reticle shake starts to make me second guess my shots. Since I tend toward fixed power optics I normally just have to deal with what's on the gun. On the few variables that I use I'll dial them all the way up to 9x on a 3-9x but I'll only dial to 12 on a 4-16x because the optical quality on that scope goes into the toilet above 14x and 12 is plenty. That's only for shooting for groups.

When hunting, always turn the scope down to its lowest magnification setting and increase it only when you need to. Don't use your scope as a monocular for glassing terrain. Use binoculars and save the gun pointing for when it's harvest time. Above all, magnification is not the thing that most people need.

Adding to what the gentleman above me wrote--and which I agree completely::

The old rule of thumb is that you need 1X of power for every 100 yards of distance for tactical accuracy.
So, you can shoot 1000 yards with a 10X scope with the kind of accuracy needed for tactical purposes.
Tactical accuracy, however, does not win shooting contests, it does put meat on the table.
So you have to decide whether you have a tactical rifle or a competition rifle.

One thing that disturbs me is the big objectives that many shooters are putting on scopes these days. There is a time and a place for 5-25*60 scopes, and something that shoots 1700 yards probably needs one. A 223 does not, a 308 is unlikely to need such power or objective size, or weight for that mater. Almost everything a 308 can do can be done with a 3-9*35 scope (competition and benchrest notwithstanding.)

I run 5-25 and 4.5-27 power scopes in Tactical Precision Matches.  There are times where I will be at full magnification during a stage (know your limits stage or past 1K yards to name a few).  However, a lot of times I'm using magnification between 10-20 power in order to be able to find targets faster.

In heavy mirage conditions, dialing back on the magnification can help that wobbling target settle down a bit

I agree.  

A decent fixed power scope is often the best choice, giving you the best optical quality for a given budget, and with 2 or 3 fewer lenses (depending on the design of the variable scope you are comparing it to)   for limited bucks, you save weight, get better light transmission, greater image brightness, higher contrast, and you don't have to deal with potential problems caused by less than perfect alignment of the moving lens elements  People give up a lot when they choose a variable if they are not willing to pay for the necessary increase in quality to minimize the downsides, but most of them don't realize it.  

40 years ago a good 6x scope was considered all that was needed or hunting, even in big flat states with ranges out to 500-600 yards. 4x was considered plenty for any shooting back east.  That hasn't changed as deer and antelope have not gotten harder to see.

On a precision rifle in the .308 or .30-06 class a 10x fixed power scope is still more than enough for a cartridge that runs out of steam for practical purposes around 800-1000 yards.

The problem is that shooters today seem to think that high magnification will produce better resolution and that's not really the case, and it starts a very vicious spiral of technical challenges.    

For a given objective lens diameter more magnification just reduces the exit pupil and delivers less image brightness and the result is a more highly magnified, but a much grainier image that actually has much less resolution.   To fix the light problem, the shooter then has to go with a larger objective lens to boost light transmission.  Unfortunately, producing the same optical quality in a larger less costs exponentially more money, so unless the shooter scale up the price of the optic in the same exponential proportion, he is probably still losing image quality.  

Even if the lens quality is the same, that 50-60mm objective now forces the line of sight 5-10mm farther above the center of the bore, creating potential issues with obtaining a proper check weld.  That's a double hit as parallax is a much larger problem with greater potential error at high magnifications (particularly above about 9x-10x), so you're potentially introducing less precise eye placement at the same time you are increasing potential parallax error.  So of course to fix that you're now adding in an adjustable objective to control for parallax error - adding additional, weight, length, cost and fragility to the scope.    

At the end of the day a telescopic sight is needed primarily to enable you to see the target -  as if you can't see it, you sure as hell can't hit it.  In that regard, if 8x or 10x is enough to allow you to see the target well enough to hit it, that's all you need. Period.  Any additional magnification will just decrease light transmission, image brightness and image clarity for a given objective diameter and price point, and that additional magnification will cost you in terms of field of view.  

So...if you're shooting gophers or prairie dogs on bright sunny days at ranges from 100-500 yards, more magnification might make sense.   If on the other hand you're shooting medium game sized targets in wooded areas with low light levels and deep shadows, you need less magnification, but better light gathering capability and higher image quality.

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For what it's worth, the USMC used 8x Unertl scopes in Vietnam on it's .30-06s and .308's, before eventually adopting a rather fragile and not very moisture resistant off the shelf 3-9x Redfield design, before going with a 10x Unertl design as standard for a quarter century on it's .308 rifles.   About a decade ago they switched back to a variable, but it was still a modest 3-12x50mm design by Schmidt and Bender.  

It's important to put that 8x to 10x standard for so many years in context though.   The basic zero used was normally about 500 yards and with a .308 the anticipated engagement range was 500-800 yards.  Closer than that increased the risk of exposure and much longer than that was pushing the .308 father than was prudent.  So 10x was plenty for 800-900 yards, but it was not too much for 500 yards.  At 200-300 yards however, 10x is a problem as a moving target can quickly end up outside the field of view.  In that regard a 3-9x or the current 3-12x choice makes some sense.

In the field, it's easy to find yourself in a situation where you have too much magnification, but it's pretty difficult to find yourself in a situation where you don't have enough, so keep that in mind and don't go crazy with the magnification.

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I have a 3-9x40 on the .308 I use for deer and antelope hunting, but I generally leave it on 6x in wide open spaces as it's a good compromise between magnification and field of view - and I know what things look like at various ranges at 6x.  If you mess with the magnification all the time, sooner or later you'll take a fast shot and mis estimate the range as you're looking through it at a higher or lower power than you thought.  

If I'm setting up on a ridge before dawn and watching antelope walk into range just after sun up, light permitting, I may set up a precision shot at 9x.   However if I quietly walk over the end of a draw and catch an antelope trotting up the other side at 150 yards, I want a low enough magnification to allow me to quickly acquire the target, track it and shoot it, and that won't happen at 9x.

To expand on this:

I use a fixed 24x scope for competitive shooting @ 50Y, 50M, 100Y, & 100M.

I cannot dial the magnification back, but what I can do is dial the focus 'out' slightly. Taking the shots is part timing - between the pulse beats. Once the timing is dialed in on the sighter bull (at the top of the target), I then use the out of focus objective to pick up the mirage condition. Although the course is flagged, the flags are the last thing to react to the wind - mirage will tell you exactly what the wind is doing right now. With the 24X scope, I can pick up exactly 2 and 1/3 of the 3 bullseyes @ 100Y/M. I shoot the NRA A/25 or A/33targets from top to bottom, and I can easily shoot the middle bull, while watching the mirage condition sweep across the lower bull which is closest to the ground. It sounds crazy, but it works.

Another trick for rifles on a rest or similar is to watch the target in the scope of the <unmoving> rifle to see the extent of the image movement (or vibration or distortion) L<->R and T<->B. The proper aim point is the middle of this vibration image zone created by the moving air.

Gauze through the scope until your eye has developed a feel for the size of the vibration (?distortion?) pattern and then use that to aim the rifle. Then wait for a round of limit verification, and you are ready to finally fire.

When sighting in, I start with the highest power then check it going down, for any drift cause by the optics.  These days most scopes are pretty good.  In the field (hunting) if I am in a stand I keep the scope at the middle of the range, for me 6x and crank it up after I see game and need to place a shot.  When moving in the woods or in civil twilight conditions I turn the scope down because it gets more light to your retina due to the increased exit pupil of the scope.

I like 6x the best  for my ar15. I have a 3.5-10x40. I feel 6 x gives me the best balance  between field of view and magnification. I did dial up to 10 yesterday when shooting out to 850 on standard Ispc sized targets. I even hit the gong at 900 but that is 36” and round

Looking for recommendations on a good starter variable scope, haven’t picked out a rifle yet either so I guess that would be cool to hear also. I have rifles just not a marksmen hobby dedicated rifle yet. Thanks in advance