Leupold VX-III 4.5x14 - 40mm W/ B&C Reticle

badlander · Jul 9, 2007

LAST EDITED ON Jul-09-07 AT 08:35AM (MST)[p]I just purchased this scope for a Tikka T3 in .270WSM.

I am shooting factory ammo - Winchester Supreme 140g Accubonds. This ammo is quite a bit flatter shooting than the B&C reticles are set for at 300, 400, 450 & 500.

Does anyone here know how many inches of drop those tic marks are actually calibrated for (at large triangle [14x])?

For example, I played with it a little bit this weekend with some measurements on paper I think 400 is calibrated for a 20" drop - zeroed at 200 - crosshair dead on the target the 400 yard triangles fell on 20" below the bull. (the ammo trajectory however is about 16" however. I am trying to find out what actual yardages are dead on for each of those tic marks?

I am looking for something a little more accurate than me eyeballing it trying to look at 1" squares at 400 & 500 yards through the scope?

Boskee · Jul 9, 2007

The easy solution to this is to call Leupold. The next best thing is to get a hold of a reloading manual and if you know the velocity of your cartridge then it should be easy to figure out using the correct bullet weight and type from the trajectory tables in the manual. There are a couple of other ways that are too time consuming to go into here. You can always raise your zero at 200 and it should put you real close at the longer yardages if I understood your post correctly. Then you could always shoot a few at 300 & 400 and adjust your scope accordingly to be high at 200 and just move your target out till you're hitting dead on if you have to know exactly. Given that the trajectory of a specific bullet normally remains fairly constant at an established velocity the reloading manual trajectory tables should be an easy fix. Thats how they were able to make a compensating reticle for your scope and get it to work on an animals kill zone over a broad range of calibers. Hope this helps.

BPKHunter · Jul 10, 2007

Try this:

http://www.boone-crockett.org/news/news_leupold.asp?area=news

Then go here:

http://stevespages.com/page8b.htm

and download this simple ballistics/reloading software:

POINT BLANK COMPUTER RELOADING AND BALLISTIC SOFTWARE ver. 1.8a

The first one will tell you the preset drop data.

The software can be used to give you a pretty good idea of your impact boints at the various yardage marks. You will need to know your bullet and the muzzle velocity.

I have the book, Hunter's Guide to Long-Range Shooting by Wayne Van Zwoll. It lists ballistics for most of the popular factory loads. He shows a Winchester 140 Accubond(I assume they only load accubonds in their Premium rounds). For that round he shows:

Muzzle Velocity: 3200
Muzzle Energy: 3184

Yards Velocity Energy Arc

100 2989 2779 +1.2
200 2789 2418 0
300 2597 2097 -5.7
400 2413 1810 -16.5

You should be able to basically build this chart in the Point Blank Software, then change your Zero and see how it effects your downrange drop. If I change the zero to 300 yards, then the arcs for 100, 200, 300, 400, and 500 are: +3.0, +3.7, 0, -8.6, and -23.0 respectively. Also, all these numbers assume 80 degree temps at near sea level, if your like me and will hunt at 8000' when its 20 degrees, you can change those parameters in the software.

Good Luck.

Brian