Question on verifying velocity

[Jarhead6870]

The three thi

I have a question and curious your experience. I went out the other day and shot two rifles with new bullets and loads. Started out with my MagnetoSpeed and then shot out to 600 yards to verify data. After data verification both rifles showed the speed of the bullet about 100 fps faster than my chronograph showed after verified at longer ranges. My question is whether my Magneto speed is accurate or off by 100 FPS

I've alway had minor adjustments in data when verified out to longer distances but 100 fps seems much? Thanks

While scope tracking is critical, I do not think BOTH scopes would be off equal in their turret correction factor thus giving you a false reading.

Two different rifles giving you the same velocity correction would indicate a couple of things to me:

1. I would assume that BOTH rifles have the same inputs in your ballistic program. This would be a reason that they BOTH gave you the same correction. Check and then double check ALL inputs and verify they are correct.

2. One of the biggest issues I see is the assumption of the target distance used for the muzzle caliberation. If you did not range the target yourself, then you're trusting someone's say-so of the yardage, which I NEVER do. Range or measure it yourself to know it's correct.

As for tweeking a ballistic program, many of us will adjust muzzle velocity out to 500-600 yards and then tune the BC for distances beyond for the reasoning that velocity has more of an impact than BC at shorter distances. I use a stepped BC for many of my long distance cartridges to adjust for the change in BC as the velocity changes.

Hope this helps...

 

[rcol317]

Thanks for all the input. seems the issue is BC of the bullet. I tweet the BC a little and the drop data is in line with the verified data. By verifying data I have shot at 300-800 yards in 100 yard increments and verified the drop I experience with the drop data by my Applied Ballistic AE program based on calculations from velocity of the bullet. All targets were placed by me and verified by two range finders so confident the actual range. Seem the BC of each bullet is a little different than the published data from Berger. Thanks again.

 

[CharlieNC]

When correcting based on target results, be sure to account for the environmental conditions. Going by a single range session is not as reliable as averaging the results from different conditions as wind, light, mirage, shooter, etc have a significant effect.