223 zeroing

[shotgun sam]

A quick question I am sure someone will advise me on.
My usual zeroing area on the farm has been shortened to 75 yards as the farmer has temporary storing some lorries.
I would like to have the rifle zeroed for 100 yards how high above the center point will replicate that

[1066]

Not enough to to worry about..with just a guess at your bullet weight and speed of 55gn and 3,200 fps it looks like you'll be .16" low at 75 yds

[Sim G]

Yep, just as he says....

For S&G just ran 55gn Sierra Blitzking at 3250fps for a BC of .271 through the calculator and 75 to 100 yards is a 0.1” variation.

[shotgun sam]

Thanks 1066 and Sim G

[breacher]

Difference is so tiny you wont notice.

[Mattnall]

Difference is so tiny you wont notice.

Yep, and if you do want to off-set you'll most likely need to be below the aiming mark not above it.

[Phoebus]

I happened to zero my .223 yesterday at 100 yards and using my ballistic info, I'd be 0.2" or 5mm out at 75 yards but I'm running an 18" 1-9 twist barrel shooting 55gr's at 3240fps. Either way, it's negligible really.

[IainWR]

If you have a fairly high line of sight above the line of bore that may be much more significant. You will need impact 1/4 of the distance between scope and barrel below the target to get a 100y zero at 75 yds, less the tiny little bit for gravity drop from 75 to 100.