1. ## Hornady .308 165gr SST - Trajectory Question

Looking at the trajectory on the Hornady website, it says that with a 200 yard zero, it's going to be 1.8 inches high at 100 yards. This may be a stupid question, but how does that translate with a 100 metre zero at 200 metres? 1.8 inches low?

Hornady Manufacturing Company :: Ammunition :: Rifle :: Choose by Caliber :: 308 Win :: 308 Win 165 gr SST® Superformance®

Thanks in advance for any help.
Cheers
T_T

2. TT,

There are no stupid questions...just dumb answers!

The bullet will describe an arc or more exactly a parabola. If you think about how the bullet reaches the 200m mark it is because you need to angle the muzzle upwards to describe that flight....at a 100m zero you will have the muzzle lower. Gravity will affect the bullet from the moment it leaves the barrel so by the time it comes to the 200m mark when zero'd at 100m it will be well below 1.8inches....

Bottom line is you are looking at a 4.5" drop on a 165SST for a 100m zero at 200m!

3. Brilliant! Thanks a lot for the help.

4. 2-0-9 , 2" high at 100m 0 at 200m and 9" low at 300m , works there or thereabouts with all common deer type calibres , certainly good enough to get killing hits.

5. Originally Posted by Dorsettaff
TT,

Bottom line is you are looking at a 4.5" drop on a 165SST for a 100m zero at 200m!
Mixing units of measure makes this rather confusing. Better to use inches and yards or millimeters and meters.

Anyway, 4.5 inches seemed rather much to me given that it would be more than a 2 MOA change at short range. I used Hornady's calculator with their publsihed BC (0.447) and muzzle velocity. That predicts an impact 3.5 inches low at 100 yards this of course is 1.75 MOA. When applied to meters where 100M = 109yds and 200m = 218yds the diference will beinfinitesimal.

6. Originally Posted by MARCBO
Mixing units of measure makes this rather confusing. Better to use inches and yards or millimeters and meters.

Anyway, 4.5 inches seemed rather much to me given that it would be more than a 2 MOA change at short range. I used Hornady's calculator with their publsihed BC (0.447) and muzzle velocity. That predicts an impact 3.5 inches low at 100 yards this of course is 1.75 MOA. When applied to meters where 100M = 109yds and 200m = 218yds the diference will beinfinitesimal.

4.5'' drop at 200m with a 100m zero sounds about spot on to me ?

7. Originally Posted by tackb
4.5'' drop at 200m with a 100m zero sounds about spot on to me ?

Reminds me of some guys that used to work for that relied on "I think..." I feel..." and "I believe..." No facts could dissaude them.

8. Originally Posted by MARCBO

Reminds me of some guys that used to work for that relied on "I think..." I feel..." and "I believe..." No facts could dissaude them.
in fact I know it's near enough spot on as I've actually shot these bullets in my 308 at most ranges and the 168 amax plus many other different bullets , would you care to use some of your facts to show me where I'm wrong ? I don't mind imperial or metric or a combination I'm familiar with either ?

9. Originally Posted by tackb
2-0-9 , 2" high at 100m 0 at 200m and 9" low at 300m , works there or thereabouts with all common deer type calibres , certainly good enough to get killing hits.
Yes, most standard deer cartridges are going to be about about like this. If you think you will be shooting at 300, get the holdover exactly where you want it at 300 ( eyeball, ballistic reticle, Mil Dot, or to the duplex at a certain power), then shoot to find the drops at 200 and 100. It may come out to +2.25 at 100, +0.5 at 200, and -7.0 at 300. The odd 1/4 inch at shorter ranges are easier to ignore than some large and oddball value at 300.

Edit: English units ( the way I think, yards, inches, MOA, 1/4 inch clicks)
165-gr .308 bullet at 2,800 fps with a BC = 0.450 approximately
Drops in inches...
A hot load (2,900 to 3,000 fps), same sight setting changes 300 to -7.0, 400 to -20.0, 500 to -40.0
 Muzzle 100 yds. 200 yds. 300 yds. 400 yds. 500 yds.
 2800 1.8 0 -7.6 -22.1 -44.7

10. Originally Posted by MARCBO
Mixing units of measure makes this rather confusing. Better to use inches and yards or millimeters and meters.

Anyway, 4.5 inches seemed rather much to me given that it would be more than a 2 MOA change at short range. I used Hornady's calculator with their publsihed BC (0.447) and muzzle velocity. That predicts an impact 3.5 inches low at 100 yards this of course is 1.75 MOA. When applied to meters where 100M = 109yds and 200m = 218yds the diference will beinfinitesimal.