OK OK,
Geez I miss a couple of days here and you guys throw me under the bus! Lots of good points here. As well as lots of good gear mentioned. There are others that were left out that are good gear as well but lets move on.
The answers on fixed vs. variable are excellent and should include the point that estimating a target size is more inconsistant when done at various magnifications. Also, though most newer optics do not loose there optic center upon increasing or decreasing power, many shooters do. This is where eye relief is extremely important as well.
Big point to ponder; if you are buying this for true tactical use or for rapid aquisition and firing, consider this ...
Adjustable objectives, focus knobs or any other name you may hear for parallax adjustments are handicaps for this type of work. Here's why;
At the critical moment of firing there are several factors to deal with. Posture, breathing, movement, trigger control, stock weld and certainly thinking. Now add the fact that ... **** MY OBJECTIVE IS OUT OF FOCUS!
By the time you re-adjust and get back on target, you can easily loose your window of opportunity as well as compromise yourself via movement. All bad.
There are scopes on the market that are parallax corrected to a specific distance and will still remain in focus at other distances as well. This simply reduces your mental and physical requirements by a substantial amount and increases effectiveness.
Now the down side, there is an error factor involved with parallax corrected optics at uncorrected distances. It can amount to a significant amount at extreme distances. This will not be a detriment on a killing rifle for a trained operator. It will be a factor to a match shooter needing accuracy at it's technical limits.
I realize I have gone long here but I really enjoy this topic and hope this helps.
For one last thought, if you are at a point in your shooting where you are still learning and improving rapidly, I suggest you NOT spend a fortune on optics. Get something stable and solid with good turrets and decent glass, mount it well on your rifle and spend your money on match ammo so you can continue to improve. When you are consistantly shooting as well as the limits of your equiptment, then get better stuff.
Feel free to email me for prices on any of this stuff. I have been doing this for a while and can probably save you money. Bear with me if it takes me a few days to respond. We are busy.
Here's to the V-ring,
Duane Dwyer