Truing a ballistic app

[BANG...ping]

Hi everyone,
I need to tru my ballistic App. I only have access to 100, 200, 300, and 1000 yard distances. Will shooting paper at these distances provide enough data to true my ballistic App? Or do I need to shoot paper at a few additional distances at 300-1000 for more data? I' m new to this and any info will be helpful.
Thanks,
Bang

 

[Wiley Coyyote]

Some ballistic apps have slots to enter more than one distance along with elevation settings. Most only have a slot for one. I try to shoot a decent group at about 85% of the distance to where my round enters the transonic zone and goes subsonic. At my elevation that is about 1120 FPS. Practically this works out to be a bit under 1000 yds for my 308. I have a target at 850 so conveniently use that to true the 308. 1325 yards for the 300 win, as have another convenient target at that distance.

Recently I got a MV of 3010 with my magneto speed. Happened to shoot a tight group at 1100 yards and Ballistic Arc trued that to 2999.5 FPS. Next day I happened to get a tight group at 1325 and BA trued that to 2999.5 again. So I am calling it good at 3000 FPS.

good luck and don't over think it

 

[BANG...ping]

Thanks Wiley for the good response.

 

[DocUSMCRetired]

Do this experiment. Shoot at 300 yards and 1000 yards. 5 shot group. Then take the lowest shot in the group, and run a muzzle velocity calibration with it. See what that shot would equal for MV. Then do the same thing with the highest shot. Subtract from the high shot, and see what the spread in MV looks like. That's just about what the spread in DSF would look like had you done the same. The further you shoot, the less natural error you will have.

 

[BANG...ping]

Thanks Doc for the response. But can you explain what the DSF is?

 

[DocUSMCRetired]

Thanks Doc for the response. But can you explain what the DSF is?

Drop Scale Factor, its a scaling coefficient basically that gets applied to the CDM in order to make any corrections a user wants to.