BA not lining up with dope on scope

[JohnS.]

not sure where to go from here.
Strelock and Sig BDX call for 1.8 mil for 100yards. my actual scope setting is 1.5 mil

at 300yard sig and BDX call for 13.7 mil. my actual scope setting is 13.3 mil

Bergara B14R
Eley target @ 1110 FPS Actual
50 yard zero

is it within reason to be a few tenths off or could it be a scope issue

Can the Sig BDX be corrected to be on line

 

[Huskydriver]

You need to true your curve on the bdx or strelok to get the curve close to your actual dope

 

[JohnS.]

You need to true your curve on the bdx or strelok to get the curve close to your actual dope

is that done with playing with velocities

 

[Huskydriver]

is that done with playing with velocities

Or the bc within reason yes

 

[JohnS.]

Or the bc within reason yes

ok, ill try the BC.

 

[Huskydriver]

ok, ill try the BC.

I wouldn't play with the bc until you try the velocity first

 

[PinesAndProjectiles]

I'm wondering if it's something else.

Seems odd that you're three-tenths off at 100, and four-tenths off at 300, both in the same direction.

I would think if it's a velocity or BC issue, the needed vs actual elevation needed at 300 would be more.

Is your scope over bore height correct?

 

[Cowpokey]

Scope over bore height would be my guess.

 

[DFOOSKING]

I'm 1175fps with yellow SK and require only 1.6 for 100yds. Weird your dramatically slower but less dope.

Make sure your dope is checked to be "on the water line " on the steel/target.

 

[jbell]

Agreed, 1.5 mil from 50 to 100 seems odd for me too. Granted your MV is 40-50 FPS faster than what I am used to & I have never shot that ammo, but I would first confirm your zero distance is actually 50 yards and the target in question is actually 100 yards. I am used to seeing 1.8-2 mil drop from 50 to 100 depending on the ammo and barrel I am shooting it out of. After that consider the air temp when zeroing, was it significantly colder than when you shot this at 100 yards (I have seen a tenth or two loss in extreme cold).

It may not be just one single thing but rather a few things working together. Start with making sure all parts of the equation are accurate and consistent.

 

[huntnh]

Check distances mine wasn’t lining up so I bought the range finder to my range the 50 was actually 45 and the 100 was 107

 

[JohnS.]

I'm wondering if it's something else.

Seems odd that you're three-tenths off at 100, and four-tenths off at 300, both in the same direction.

I would think if it's a velocity or BC issue, the needed vs actual elevation needed at 300 would be more.

Is your scope over bore height correct?

Yes scope bore is correct.

 

[JohnS.]

Check distances mine wasn’t lining up so I bought the range finder to my range the 50 was actually 45 and the 100 was 107

Checked distance: 50 yard is 51 and 100 yards is 101.
Bore height is correct
I checked MV with chronograph
I am using sig kilo3000 with the phone app
Backing up with Strelock pro. Both give me the same solution.

the range I shoot at is limited as far as what we can shoot ie: 25,50,65 and 100. I had a one time chance to go out to 300 hence why I have that dope.

Im actually thinking the scope might be bad.
vortex diamond back 4-16x44 FFP

 

[Fowlmaster]

I would true your curve. That should take care of it.

 

[THEIS]

Hi,

Why would you say the scope is bad just because your real target data doesn't match your ballistic app data.

Of THOSE items the ballistic data would be the one that is "bad" and it is not bad; it just hasn't been trued to your setup.

The BC the manufacturer gives is based off their MV, their environmentals, their test barrel lengths, etc....yours will be slightly different.

Sincerely,
Theis

 

[JohnS.]

I would true your curve. That should take care of it.

When you say true the curve, what is the process other than playing with velocity and BC.

 

[JohnS.]

Hi,

Why would you say the scope is bad just because your real target data doesn't match your ballistic app data.

Of THOSE items the ballistic data would be the one that is "bad" and it is not bad; it just hasn't been trued to your setup.

The BC the manufacturer gives is based off their MV, their environmentals, their test barrel lengths, etc....yours will be slightly different.

Sincerely,
Theis

I’m using two different Ballistic apps giving me the same solution.

 

[Defender32]

I would highly doubt there is a scope problem. I would re measure bore height to center of optic. I would triple check distance with range finder. Get a few 10 shot velocity averages. Then I would true data beyond 100 yards out to 300 or 400.

I am going through the truing of data with my kestrel now. 50 yard zero is 1.8 low at 100 with SK rifle match at 1070-1075 average for me.

 

[Defender32]

When you say true the curve, what is the process other than playing with velocity and BC.

Truing the curve is inputting real world data into the solution.

If the data called for 13.5 at 200 and it was actually 14.2 you would adjust it to 14.2 and the system will know that is true data and make the adjustment for the rest of the distances. Then go to the next distance and repeat.

Kestrel on YouTube has a few videos explaining it. They are explaining it for CF, but it does the same for rimfire. It also needs to be done 100 and beyond. I just started learning and reading about it myself and this is what I have gotten out of it.

 

[THEIS]

I’m using two different Ballistic apps giving me the same solution.

Hi,

Both run the same ballistic algorithm so they should match when the exact external data is dumped to them.

Sincerely,
Theis

 

[Fowlmaster]

When you say true the curve, what is the process other than playing with velocity and BC.

I true my curve using the kestrels. A chrono is good and all but it does not provide real world drop data. So sight in dead nuts at 50 which will be your zero. Drop back to 200 and get your real world dope. Calibrate your MV in the kestrel by using real world drop data and it will provide your true MV curve. I use the DSF function every 50yds beyond 200 to true the drop out to 500. Use this data in your RF and you will be golden. Hopefully this makes more sense.