500 Yard Zero

[highscore]

Thinking about shooting Camp Smith the end of the month and don't have a 500 yard zero from 300. Anyone care to share? . AR, 223, 80gr. Sierra, 24.5 grs varget, not that it matters that much! Not sure they will actually shoot 500 but am hoping, thanks.
Bob

 

[OreoTSi]

I think It's about 7-8 minutes.
Looked at my notes, I only shot 500 once last year.
With 1/2 Minute sights and a 1/7 twist shooting 77's I was:
200 to 300- 2 minutes
300 to 500 - 5.5 minutes

 

[DrBurnsides]

What twist do you shoot for 80 grainers?

 

[mac1911]

im trying to get better at knowing this stuff....... from a 300 yard zero i came up with aprox 12min of correction?

those 80 grainers should shoot at 500!

 

[PatMcD]

300 to 600 is going to be 10-12 minutes, depending on your load and hold. 11 will put you in the black; adjust from there.
I've never shot 500 yds, but if I were to, I'd drop 2 or 3 minutes from my 600 and see what happened.

Both 77's and 80's will hammer from the long lines.

 

[highscore]

What twist do you shoot for 80 grainers?

Sierra's box says to use a 1:7 - 1:8 twist barrel. I use a 6.5 twist that I went to when I was shooting 90 grains for long range and is exceptionally accurate or at least it was when my vision was better! I can't imagine that a 1:9 wouldn't efficiently spin them though.

 

[highscore]

Thanks for the come ups. Pretty well in the ballpark of what I would have gone with if I had to guess. My ballistic program doesn't work in my current computer.

 

[PatMcD]

Sierra's box says to use a 1:7 - 1:8 twist barrel. I use a 6.5 twist that I went to when I was shooting 90 grains for long range and is exceptionally accurate or at least it was when my vision was better! I can't imagine that a 1:9 wouldn't efficiently spin them though.

1/9 just doesn't get it done with 80's or even 77's.
I've heard that if 1/9 is what you have, try the Hornady 75 Ballistic Tips.

 

[mac1911]

1/9 just doesn't get it done with 80's or even 77's.
I've heard that if 1/9 is what you have, try the Hornady 75 Ballistic Tips.

I tried hornady 75gn match with 24gn Varget through my RRA A2 1/9 from the rest.
It didn't do well...maybe a better barrel and free float would help ?

 

[PatMcD]

I tried hornady 75gn match with 24gn Varget through my RRA A2 1/9 from the rest.
It didn't do well...maybe a better barrel and free float would help ?

Probably not. 1/9 is really marginal for anything above 69 grains. One in a while one will shoot 75's, that's why I suggested a try with them.