gibbs .451 sight in for 500 yards

[juanvaldez]

An older gentleman I know is trying to get a ball park on how high to set his sights to get him close on 500 yard range. He is shooting a 530 grain PP boolit cast from a Buffalo arms mold with 85 FFF behind it. Can anyone help out with this? Just a starting point to get him close would be great.

Cheers

[docone31]

If he has a long range, or midrange sight, he could start with sight line higher than the top of his factory sight. A lot of factors will determine the result, but, he can move the aperature up to that point and start there.

[rhbrink]

It would be hard to say without a starting point, does he have a 100 or 200 yd. sight sitting?

[Nobade]

If you have a 100yd zero, try about 67 MOA up from there for 500 yd.

[405]

Nobade, Si! My calcs run pretty close to that at about +65 MOA adjustment (or raise rear sight 2/3" above the 50-100 yard zero setting) to get ball park at 500.
I used lots of assumptions for that SWAG like guessing BC, MV, basic sight setup on gun, sight radius, etc.

[juanvaldez]

So I got some data from my rifle today too and I could not get it on at 500 yards.

Here is what I have

70 grains of 3F
Steve Brooks Round Nose 295 Grain Boolit
27 on the Vernier Sights for 100 Yard 0
36 on the Vernier Scale for 200 Yard 0
Boolit MV is 1495 FPS

Anyone able to calculate wher the sights need to be from this info for 500 Yards?

Thanks!!

[405]

jv, Don't know if our WAG was close with the Gibbs??
For yours... what's the caliber?

[juanvaldez]

jv, Don't know if our WAG was close with the Gibbs??
For yours... what's the caliber?


.40 cal

I'm calculating about 50 points more on the vernier scale with a BC of .30 for 500 Yards based on what I got today so 75 for 500 yards does that sound close?

[405]

Yessir,
Your baseline data helps validate the predictive calculator. Your numbers seem to be very close! We may be using the same calc. :)

The WAG for 500 yd zero is your 100 yd setting plus 48 MOA = +75

The WAG for 500 yd zero is your 200 yd setting plus 39 MOA = +75

I really like the NORMA ballistics calculator-- I think they dropped their English version but they still have their Swedish version. Don't ya know... yah

Here's a link to another handy one but takes a little more piddling with.

http://www.eskimo.com/~jbm/calculations/traj_basic/traj_basic.html