Need help calculating how high to sight bullet at 100 to hit at 500

[ThorBird]

Can anybody with the Sierra ballistics program, or any program, help me out and tell me how many inches high I need to be at 100 yards to be on at 500?

I have 2 guns I need to know this for:

The first is a 6BRX with the Berger 108 BT (.243) traveling at 3050 FPS.

The second is a .308 with the 168 SMK (.308) traveling at 2,700 FPS.

The following is the same for both: They are both zeroed at 100 yards. The altitude would be 2,000 feet above sea level and temps at 75 degrees.

I can’t find my Sierra program and I need this information by Saturday so I don’t waste a bunch of ammo getting on target. My guess is that I probably need to be about 9 inches high at 100 for the 6BRX, and about 11 for the .308?

Thanks so much to anyone who can help me out.

[snipecatcher]

I use this to get an idea of drop/drift:

http://www.handloads.com/calc/

[jpdown]

Here is a free program to calculate what you need. You'll also need the bullet BC to calculate.

http://www.huntingnut.com/index.php?name=News&file=print&sid=3

[bodywerks]

You are in range with both estimates.

[memilanuk]

http://www.jbmballistics.com/cgi-bin/jbmtraj_simp-5.1.cgi

[ThorBird]

Thank you guys for the great links and your feedback. Looks like I won't need to buy software for that need again.

[kschilling]

I use those exact numbers for my BRX and my .308. Our Vel numbers are not that far off.