Drop Charts from Sierra not matching up.

[CHARLIEDUECE65]

I have a 243 Winchester. I am shooting the 105 Amax with H4831sc powder and BR2 primer. Anyways, I printed out a drop chart based on the above load with GM210 primers I had chrono'd awhile ago. The drops aren't accurate at all. My 200 yard correction was 4 clicks at 1/4" click value on a leupold scope and the 300 was 10 clicks total. The sierra data says 5.3 at 200 and 13.4 at 300. Is this normal? I tried to adjust the velocity higher on the sierra load data to see if I could match the real world data but couldn't. I see the 200 yard data is fairly close but when you get to 300 its starting to get aways off and will probably be even more the further out I shoot. Is there a more accurate program or is it me?

 

[midwesthunter]

I would start by giving us ur load data u came up with. I'm not sure how much different the different primers will effect velocity.

 

[Broz]

Are you sure your scope is zeroed and holding zero?

Is the scope mounted high off the barrel?

Just a few things that came to mind.

Jeff

 

[CHARLIEDUECE65]

I'm using 45.5 grains of H4831sc. The scope works great, not the most expensive by any means, but it tracks great. I had it sent to leupold for target turrets and a new reticle this last summer. I've tried all types of powder and bullets and this combo works great in my rifle. The barrel is 25" long and an 8 twist. The scope (3.5x10x40) is in medium leupold qrw rings and bases so it sits pretty close to the barrel. I've got my adjustments out to 300 now but would like to make a chart that represents what I'm actually seeing in the field.

 

[Broz]

What will be your maximum range?

Jeff

 

[CHARLIEDUECE65]

I went with 500 as it could be possible but limited to my scope power. I corrected the scope magnification it is a 3.5x10x40 on this rifle, I was thinking of another scope.

 

[Broz]

I went with 500 as it could be possible.

I would just shoot to get actual drops at every 100 yards and maybe at 350 and 450 too. Log the MOA up at each distance and then make the ballistics program match up by changing the BC and Velocity a bit. I would start with velocity and emember a lot of chronographs will lie to ya if you let them. When done print it and you will know you have good data.

Jeff

 

[CHARLIEDUECE65]

I kinda figured that would be the most accurate route. Thanks for the replies.

 

[bigngreen]

If you're data is tight, scope high measured with a caliper, zero dead nuts on and eviro data on you can shoot your data and run it through a program with trajectory validation. I don't know about Sierra but the G7 program in the LRH tool bar has trajectory validation, you could then take the corrected data and use it in what ever program your using then make minor adjustments if needed. You could post up your shot data and someone will run it through Exbal also and trajectory validate.

 

[CHARLIEDUECE65]

Well my scope height probably isn't right, I went with the default of 1.6 and obviously my muzzle velocity wasn't right. Everything else temp, barometer, and altitude were put in before I left for the range. I tried adding faster velocities but the drop corrections from 200-300 still weren't close. What are people seeing the B.C. of the new Hornady Amax coming in at. I think the Sierra data has them at .500. I shoot these in my 6 Dasher at 600 for F-Class and they shoot superb.

 

[CHARLIEDUECE65]

Well, I went out shooting again, adjusted the scope down to zero and back up ten clicks and shot at 300 yards again and the gun is right on. I'm wondering if maybe the 1/4 click value of this scope isn't exactly on. Could this be the problem? I've tried several other programs and they're giving me the same or close to the same adjustments as sierra.