650 fps Slow Barrel??

[JLS]

It's calculated based on: I figured out what my velocity would have to be in order to be zero at 200 meters and 4.5" high at 100 meters, which is what I was experiencing. Velocity would have to be 2100. Using 2100, I plug in 100 yards as my zero and look up what the bullet drop would be at 300 yards (because Gerald Martin suggested he was 16" low at 300 yards with a 100 yard zero, I wanted to compare apples to apples). It would be 26" low.

Until you calculate it based on actual drops and have a known MV you are spinning your wheels. Calculators don’t mean shit with unknown variables.

 

[ozzy-yyc]

Until you calculate it based on actual drops and have a known MV you are spinning your wheels. Calculators don’t mean shit with unknown variables.

Knowing actual drops is all you need to get a pretty good estimate of MV. Ambient conditions are very well known, as is the BC of the bullet. The estimates on those variables is a) quite close to reality and b) being wrong on those variables does not account for the magnitude of difference seen in the path of the bullet. MV by far has the biggest impact on bullet path, and conversely, known bullet path (i.e. drops at different ranges) is by far the best indicator of MV.

 

[ImBillT]

I doubt that you had a bad box of ammo unless you shot both ranges with with the same box. Changing ammo usually requires a sight adjustment. That’s one of the reasons that I prefer reloading. Im glad you worked it out though. For anyone reading who likes to use drops to determine velocity here are a few tips that I have found valuable.
1. Use the correct sight height. Measure the center of your bore to the center of your scope tube.
2. Use at least three distances and measure them with google earth or OnX. Do not trust the distance claimed at the shooting range. Even 1-2yds makes a difference.
3. Use five shot groups or larger to determine the center of the group. Even a small difference between where you’re actually sighted in and where you think you are can make a big difference, and when you have one high and two low it’s hard to tell the difference between being sighted in at the center of the group, or actually being sighted in at the two low shots with the high shot being a fluke. .1” matters a lot when using this method to check velocity.
4. Use the correct elevation above sea level.
5. Use the correct temperature.
6. Use the G7 BC or velocity adjusted G1 BC for ranges over 100yds.