Zero Targets

[Gerry939]

When at Bisley I can buy a Zero target for my .308, does anyone know if there is a 6.5creedmoor version of this zero Target , with different bullet weights...or not...just need a simpler way to check zero ....

[TattooedGun]

Weight is not the deciding factor.

Speed and BDC is.

As far as I'm aware there is not a 6.5 creedmoor version of this target, but you could use a ballistic trajectory chart to determine where up the Zero target you need to be in order to be on target, if you know the ammunition you're using.

The boards are roughly 10 MOA - although they vary at different ranges as the same boards are used at say 900/1000/1100/1200) so to be on the board you have in the region of 10 MOA possibility, at 25 yards (or 71' 7" as the zero range) that would be roughly 2.5" of elevation per distance target size, and if you know that your bullet will drop say (and I'm spitballing) 4 MOA from 100y zero to 300 you'd put the centre of the first box for 300 yards 1" above aiming mark. 600 yard would be say 12.5MOA so that box would go 3.125" above the aiming mark. 900 yards would be 24.5MOA drop, so 6.125" above the aiming mark...

Etc etc.

You might even find that the zero sheet for .308 is not far out for a number of these.

Use a ballistic calculator and look at how much drop difference there is between each of the bullets you wish to use, then compare that against the .308, you might find that you're still "on" the board within the zero target, if not, use the calculations to modify the zero target to suit based on the calculated drop as mentioned above...

HTH

[TattooedGun]

Looking at the zero target, it looks like they show just the black, and not the board as the "on" markings, so nowhere near the 10MOA I stated, but the calculations I did above from a sample 6.5 creedmoor load do not look far out from the right hand .308 target:

[andrew375]

Actually it is pretty easy to make custom zeroing targets to match your rifle / load.

First you need 3 bits of important information.

Ballistic coefficient of the bullet, get this from the bullet or ammunition manufacturer.

Muzzle velocity. If you cannot get it chronographed you will have to use the figures provided by the loading manual or ammunition manufacturer. But the more accurate the figure the better.

Height of sight above the barrel. This needs to be reasonably accurate but a caliper will do. With a blade front sight this is bottom of the barrel to the top of the blade, minus half the barrel diameter. With a 'scope use a point on the objective bell, distance from bottom of barrel to the top of the bell, minus half the diameter of the barrel at that point and half the 'scope diameter at that point.

Now you need a ballistic calculator, there are lots out there, I use one called ExBal which is actually a spread sheet. Just open in a spread sheet program like Excel or LibraOffice calc and put in your numbers in the relevant boxes.

I suggest you make your zeroing distance 25 yards. 50 yards would be more precise but you end up with a zeroing target several feet high.

On the ballistics program, where it asks for distance increments, enter 25 yards.

What we are now going to do is find the height above the line of sight that the bullet will be at 25 yards to cause the bullet to intersect the line of sight at longer distances.

To do this enter the distance you want to shoot in the box marked zero distance. Zero is defined as where line of sight and trajectory of the bullet coincide. So for a 300 yard sight setting enter 300 as the zero distance. You will notice in the trajectory column 300 yards has the value "0.0". Now look back along the trajectory table to the 25 yard column and the figure there will be where you put the 300 yard line on your zeroing target. Repeat for the other distances you require.

The best stuff to make your zeroing card from is wallpaper, most of use have an odd roll knocking around somewhere. Draw a line going up the middle. Place an appropriate aiming mark somewhere near the bottom, with iron sights use a 25 yard SB prone black as this will be the correct size for your sights. Using the figures from the trajectory tables measure up the line from the centre of the aiming point and put a horizontal line across at each distance. Write on the target the load details for future reference.

Now just set up the target and shoot, winding the sights up until you are impacting each intersection line in turn and record the number of clicks needed.

I have used this method on multiple occasions and usually it has put me within 2 minutes of the final elevation. In fact with my .223 and 69gr. SMKs it put me dead on elevation at 600, 900 and 1000 yards, all I had to adjust was windage.

[Gerry939]

Thanks for that i use strelock pro., will get down the Bog and try out you method. Cheers