S&B 3-18x Meta click adjustment question

[YamaS3rider]

Hello, I recently sighted in a Steyr THB 20" .308 with a S&B 3-18x Meta. The rifle was zeroed at 100 yards. I used a mild load to fireform new brass (168 Sierra at 2375). My ballistic calculator listed a drop of 6" at 200 (0.8 mil) and a drop of 20"at 300 (1.8 mil). The S&B only has clicks, no numbers (1 click equals 1cm per 100m). The cm and mil measure very close so I clicked up 7 and the 200 was centered. When I dialed up 18 clicks for 300, I did not hit a 36x36 piece of cardboard. WTF did I do wrong? Thanks.

 

[Kiba]

The turret is in mils even if S&B labeled it 1 click = 1 cm @ 100M (yay base 10 units of measurement) so it will be much easier to calculate all your data in mils and not bring inches of drop into things.

As far as why you hit at 200 and didn't make it at 300 I'm thinking you didn't snug the setscrews on the turret tight enough after zeroing and the turret slipped when dialing to 300, but even then you should have only hit low and still made it onto a 36 x 36 target. Did you try dialing back down and shooting again at 200 and 100 to see if it dialed back to zero properly?

I doubt that the scope is out of elevation adjustment (doubtful even on a 0MOA rail as the 3-18 has 30.5 mils of elevation travel which should be plenty.)

I'd verify zero and resnug the elevation turret screws first, and you may want to lock the rifle down and dial a tracking test on a tall target to see if the scope is tracking properly.

 

[YamaS3rider]

The manual states the posicon can be set to 0 by loosening the phillips screw. I have not done this yet until I do some higher velocity load testing. The zeroing was done by bore sighting with 3 shots, correcting the elevation/windage after each shot. Subsequent load testing always held zero. That is why i was surprised when i could not hit a huge target at 300yards.

 

[Kiba]

Do you have the posicon turret where everything is inside including the little green/red travel indicator and Phillips head screw to zero the turret, or do you have the exposed BDC turret with the little range flags you can set? I have not messed with either one of those.

For the exposed BDC turret with the little flags it looks like a mostly traditional exposed turret where you still loosen set screws and rotate the turret to set your zero and then just position the little flags to reference points of your choosing.

If it's the posicon, I need to do some reading on that...

 

[YamaS3rider]

I have the Green/red travel indicator and triangle for the "zero stop."

 

[Kiba]

Did some reading on the posicon and it appears the little phillips head screw on the top is what is used to zero the turret. Dial the turret to zero the rifle, then loosen the screw, rotate the turret back to zero, tighten the screw. Seems easy enough, even with the somewhat silly needle and green/red zones to indicate where in the overall span of turret travel you are.

First thing I would try is hang a tape measure or a graduated and to scale target at a known distance and do a tall target dialing test over the entire green range of the posicon travel indicator to see if the scope dials properly. Doesn't have to be done at 100M, but the further out you can do it the greater the click spacing ends up being and that makes it easier to see if you have an issue. At 100M you would need about 3.1 meters of vertical measurements available to test the full travel range. Of course, need to hold the rifle very steady for this process (or take the scope off and mount it to a scope testing fixture.)

You can always aim at a fixed point and dial and shoot and see where the holes end up too, but that then brings the rifles accuracy and your consistency into the test; fine for checking for large scope errors though or tracking / loose mount problems that show up only under recoil.

 

[honzo]

Hello, I recently sighted in a Steyr THB 20" .308 with a S&B 3-18x Meta. The rifle was zeroed at 100 yards. I used a mild load to fireform new brass (168 Sierra at 2375). My ballistic calculator listed a drop of 6" at 200 (0.8 mil) and a drop of 20"at 300 (1.8 mil). The S&B only has clicks, no numbers (1 click equals 1cm per 100m). The cm and mil measure very close so I clicked up 7 and the 200 was centered. When I dialed up 18 clicks for 300, I did not hit a 36x36 piece of cardboard. WTF did I do wrong? Thanks.

it's possible you misdialed the clicks. If you plan to dial a lot I would just send in the scope and get the BDCII or DT23 turrets