What is the distance between the center reticle and the point where the lines thicken on the Leupold VX-III 6.5-20-40mm scope? (in terms of viewing a target at 100 yrds.)

Are you asking about the reticle style? A MilDot reticle will have several dots to use as aiming points at different distances. This scope provides for 38 different aiming points based on the distance to the target (holdover). It selects the appropriate one based on the internal rangefinder and the ballistic information you input for the cartridge you are using.

Simply put, the Mil-Dot is a way to estimate range with the scopes reticle. This type of reticle was developed for military applications. The space between the dot centers is equal to one milliradian (Mil). hence the name mil-dot. One Mil equals 3.6" inches at 100 yards, or 36" at 1,000 yards. To use this system effectively you must know the size of the target. For instance most people are an average of 6 feet tall or 2 yards. The formula used for determining range to the target is (size of target x 1000 divided by number of mils the target covers). Hope this helps FixYa up.

this could be a scope mount fault,,,but to lift the scope up with some strips of 35mm film under the eye end will raze its point of aim

3 volt type

check how big the scope lenses are and have a look on e-bay there are lots of covers on there

Leupold has excellent customer service. I'd send it back to them for eval and/or repair.

1. Step 1 Take a rifle with a properly installed BDC bullet drop compensating reticle to a rifle range. Using ear protection zero the scope reticle so that the point of impact corresponds to the center of the cross hairs at the distance you have selected - typically 100 or 200 yds.
   
2. Step 2 Determine the trajectory of the specific cartridge you have selected. There are several ways to do this. Ammo manufacturers publish trajectory and wind drift information. There are web based ballistic calculators like http://www.biggameinfo.com/BalCalc.aspx which will tell you how much your bullet drops at known distances.
   
3. Step 3 Scope manufacturers like Leupold can be a valuable source of information about their reticle: "Leupold® Ballistic Aiming System: Boone and Crockett Club® Big Game Reticle aiming system provides a series of additional aiming points to improve your ability to shoot accurately at longer ranges. Nikon also provides good information suggesting the marks on their reticle be used for zero at 100yds followed by circles below representing 200, 300, 400 and 500 yds if the cartridge travels around 2800 ft per sec. Nikon suggests the center cross hair be zeroed at 200 yds for magnum calibers traveling around 3000 ft per sec. We understant that each variation of different bullet weight and powder charge changes trajectory and a scope manufacturer can not build a different reticle for each different cartridge made so practice on the range to determine how well the marks relate to the actual impact of where your bullet strikes at a know distance is important. The one thing that people using BDC scopes typically have problems with is that a BDC scope has the reticle in the second focal plane of the scope. If the reticle was in the first focal plane of the scope the reticle would look smaller on low powers like 3x and grow proportionately larger as the power increased to say 9x top power. The problem is that while the marks on the BDC reticle correspond accurately to the bullet drop at the know distances 200, 300yds etc. What happens when you lower the power from the scopes maximum power to any other lower power is the reticle stays the same size and the field of view within the scope increases which means that the distance between these marks on the BDC reticle no longer corresponds to the point where the bullet will strike. In short BDC reticles only work at the maximum power of the scope or at a set specific power. At all other powers these BDC reticles do not accurately represent where the bullet will strike.
   
4. Step 4 The center X always remains the same. If you zero at 100 yards and you know that your bullet drops 8 inches at 300 yards you could forget about the BDC marks and hold the center X 8 inches high - that works at any power 3x or 9x and should be used at lower powers. If you zero the center crosshair at 100yds and have the BDC scope at the maximum power 9X then the first line or circle below the center X should be the mark you place on the center of the 200 yard target----- the bullet strike should hit the center. If by some chance you put the scope on 3x and placed that first mark below the center cross hair on that 200 yard target you would shoot over the top of the target. This is because as the power of the scope decreases the field of view increases the angle increase and gets wider. You can experiment with known power settings and see at a specific power say 3x what that first circle down corresponds to and make notes because at any set power what the marks correspond to will be repeatable.
   

I got this from a website, hope it helps.

the only way is to look on the internet for there address,, but its not like leupold to pass out of true mounts,,,,there one of the best mounts made,,,

I doubt if there is anything wrong with your scope.
The Baraska model A10810 Reticle adjustments are 1/8 ( 1/8 inch) MOA (minute of angle).
For instance, Look at the top turret (The ELEVATION Adjustment Knob). You will see that there are little vertical 'hashmarks' all the way around the knob starting with a '0' then a series of the verticle hashmarks, then a '1' and another series of the marks, then a '2' and so on. YOUR scope will have 8 of those vertical 'hashmarks' between each 'number'. These little 'hashmarks are referred to as 'Clicks' or 'Minute of Angle' adjustments.
Now imagine that you are set up on the 100 yard line and you have fired a round at your target, say a one inch diameter dot or any size for that matter, and the bullet strike was one (1) inch LOW and two (2) inches to the RIGHT and of course you now want your next round to impact in the target dot.
To bring your bullets point of impact UP to coincide with your point of aim (you have your 'crosshairs or RETICLES centered on the dot), you will be turning the TOP adjustment knob CLOCKWISE, ONE 'click' at a time. EACH one of those 'Clicks' will actually move the horizontal Reticle UP (Elevation) or DOWN 1/8 of an inch at a time. If the bullets point of impact was 1 inch LOW, you would need to turn the adjustment knob clockwise Eight (8) clicks which will equal ONE (1) inch.
Now you must adjust the knob on the RIGHT side of the scope. This one is the WINDAGE Adjustment knob which controls the VERTICAL Reticle and moves the point of impact Right or Left. This knob will also have the 'hashmark' increments around its perimeter and like the Elevation knob each 'Click' will move the Reticle 1/8 of an inch but in this case the Reticle and point of impact moves Right or Left.
Remember the bullets point of impact was 2 inches to the RIGHT. This means you must adjust the Reticle or point of impact to the LEFT so that your point of impact will coincide with your point of aim and will be in the target dot. Turn the adjustment knob COUNTER CLOCKWISE Sixteen (16) Clicks. Keeping your POINT of AIM (crosshairs centered on the dot), your next round should be inside the dot and you can then fine tune it from there.
As you can see from this example, the Reticle (crosshairs)and point of impact does not travel very far at all inside your scope at the 100 yard distance so it is not hard to imagine that you thought they were not adjusting to get you on target, when in fact they WERE adjusting, but in tiny increments.
Now, as you create more distance between you and your target, these 'tiny' increments and point of impact will be larger as your distance increases. For example, at 200 YARDS each 'click' will move your Point Of Impact 1/4 of an inch right,left,up, or down. So if your bullet point of impact was one (1) inch low from the 200 yd line you would adjust your Elevation Reticle 4 Clicks to raise your point of impact in order to be on target. At the 300 yd line each Click will adjust the point of impact up,down,right or left, ONE (1) inch.
If you wish, I would be happy to walk you through the 'ZEROing In' of your scope and rifle even if you do not have a Zero Bore Scope. With-in about 9 rounds you can be hitting where you are aiming instead of 'chasing' bullet holes all over the paper.
If you are interested, respond back and I will be glad to assist you. Enjoy. :)

Follow these steps

1) Mount your scope.

2) Use a bean bag or rifle mount and make sure that your rifle doesnt move much from its original position throughout this process.

3) Aim with the scope and shoot at a large backstop which will allow you to see where your shot lands, where ever that may be, it doesnt matter at this point. Again, make sure your rifle doesnt move much when firing.

4) With the rifle in the same position, look through the scope and adjust the crosshairs over to where your shot landed.

5) The scope now sighted in with the rifle. Minimal adjustment may still be required but at least your well within the ball park.

Happy Shooting