I'm researching scopes to handle 100-500 yards on my .308 at stationary targets at the range.  What's the "ideal" magnification range for shots at these distances?  I don't want to under or over purchase.

Thanks!

Nice bang for the buck would be a leupold mark Ar 6-18x40 with mildot

You won't need any more than 10x imo

If we push the max distance out to 800-1000 yards, do your suggestions on the upper range change much?

308 drops roughly 360-390 inches @ 1000yrds depending on your entire setup
Give that as mentioned 10x is good but like 20-32x at the top is def easier to see at the 600+ range

Just curious, what size targets are you shooting at?  A scope that is suitable for shooting at a man-sized torso target may not have enough magnification for shooting at a target the size of t a prairie dog.

agreed, its better to have good sight at 600yrs and be able to reach out farther if needed. once your hitting 600yards regularly your going to want to push out farther, buy a scope that will reach 800+ it will save you $$$ in the long run from buying another scope!

I'll probably mix it up a bit...not really sure as I'm just getting into 100+ yard shooting.  I'd prefer to buy once/cry one on the scope purchase.

I had a USO 3.5-17x44 and it was fine for it's intended purpose......then I started playing around in some league shoots with small targets  and simply wanted more power.  

Personally I like a top end around 22x but most will agree that on human sized targets 10x will do everything you need.  The 22x gives me versatility.

What's the lowest I should go for 100 yards?  4x?  6x?

To the original question, I say the magnification depends from your stance, your scope and the size of your target.

I have Howa 1500 Compact varmint, 20" .308win barrel. Leupold Mark4 3.5-10x40 LR/T on top of it. I shoot it from the bipod rest, from the prone stance. Nothing else, excpet the shooting matress. I mostly shoot IPSC targets and animal figured, silhouette falling plates. Both are quite large.

Longest range I have shot my Howa + Leupold combination is 550 meters. I like the best magnifications for the ranges up to 550 meters to be x6 or maximum x8. Smaller magnification gives you also an advantege to monitor the area surrounding your target more better and take notes to help your aim or impact.

Why? Because of the factors mentioned above. When I use the x10 magnification, the sight picture comes a little soft and foggy. I prefer the x6 because the picture stays very sharp and crisp. The x8 is also good. Also when I use bigger magnification, I see more jumping and moving on the crosshair, which makes me more unsecure, nervous and lowers my "self esteem" to make precise shots. When I see the wandering or moving in the crosshair (because of the high magnification), I start automatically to hone and move, trying to make my stance more "better". Usually this results a more poorer and unergonomical stance, which makes me shoot more worse. For me, smaller but reasonable magnification means more relaxed shooting and tighter groups. I think the stance also plays a big role for choosing the magnification. More stable stance, more bigger magnification you can use.

With x6 to x8 magnification my Howa shoots on a good day about 1 MOA groups, little more or little less, to 550 meters with handloaded ammo using Lapua lockbase or Nosler CC bullets and Vihtavuori powders. That means 15-20cm groups.



For the different ranges I recommend from my standpoint:

under 200m:     x4 or less
200m-400m      x4-x6
400m-600m      x6-x8

Smaller targets will naturally need bigger magnification.

Rule of thumb I've always heard was 1x magnification for each 100 yards.  That said, I love my fixed 6x as a hunting scope for shots out to 350-400 yards and I prefer a fixed 10x for most low - mid bore target shooting,  For large bore stuff, I've been using a fixed 16x.

It is possible to have too much power, especially while hunting.  Larger magnification = smaller field of view and it becomes harder and slower to find your intended target.  For my own uses, I prefer fixed magnification.  Until a 1-8x becomes somewhat affordable, I'll stick to my 6x on my hunting gun.