I would check for parallax at 400.
I have seen people shoot low with BDC reticle due to parallax error just as you describe.
Truing for BC - experience with accuracy of Barnes stated BC
- Thread starter med358-boise
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I would check for parallax at 400.
I have seen people shoot low with BDC reticle due to parallax error just as you describe.
med358-boise
Well-Known Member
4th point,
Can you explain more as I have never really understood how parallax works. I know parallax is different than focus and that scopes (unless they have a parallax adjustment) can only have parallax set at one distance.
In the PRS competition world, a common "truing of DOPE" technique is:
1) Chrono load in your rifle - input speed and bullet into one of multiple ballistic apps (Hornady 4DOP, Applied Ballistics, etc.)
2) "True" velocity to 600 - velocity is the key variable to 600 yards or so
3) "True" BC at 800 yards or as far as you can - BC is key variable at extended ranges
If you are shooting less than 500 yards - velocity is the key and BC not as much
1) Chrono load in your rifle - input speed and bullet into one of multiple ballistic apps (Hornady 4DOP, Applied Ballistics, etc.)
2) "True" velocity to 600 - velocity is the key variable to 600 yards or so
3) "True" BC at 800 yards or as far as you can - BC is key variable at extended ranges
If you are shooting less than 500 yards - velocity is the key and BC not as much
Set up your rifle so that you can view through the scope without moving the rifle. Move your head slightly, side to side, then up and down.
Do this while viewing something at 400 yards.
I bet that you will see the reticle move. Up and down, as you move your head slightly up and down. If so, that is likely the issue, especially from field positions.
med358-boise
Well-Known Member
4th point,
I may be exposing "my stupidity here" but I assume what happens then is that "I don't realize my head has moved slightly, so then I adjust the hold" and create the error?
I may be exposing "my stupidity here" but I assume what happens then is that "I don't realize my head has moved slightly, so then I adjust the hold" and create the error?
Doom2
Well-Known Member
The drop to 400 yds in most cartridge is not a strong function of BC. The usual recommendation is to true using velocity out to about 600yds and then use measured velocity and adjust the BC to match actual beyond that point. You have to remember that whether you are using G1 or G7 it's likely that neither model actually fits the bullet you are shooting so some deviations are likely to show up (Post #13 ).
