tipping and BC calculations...

[dcnyli]

So currently my 6.5x47L runs 2750fps and the AB calc is dead on with it, I am debating on using the whidden bullet tipping setup to help give me even more edge.

My question is that if my calc runs off FPS and when you true it, it correct FPS, will the improved BC from tipping and in turn better BC throw the fps calculation off, or is there a way to input correcting/trueing so it adjusts the bc to compensate?

this is with 140 Berger Hybrids, 1-8twist, 24"

 

[half]

I am currently fighting the same thing in reverse. I started pointing bullets, and using shooter on my phone. Then I bought a kestrel with AB. I am just getting started with AB so I have a lot to learn. The thing that I learned first was adjustments made to velocity have a much bigger impact on the program, than adjustments made to BC. If your not changing your velocity just increasing your BC by 5%, you may not need to change much at all.

 

[Rudie]

I'm currently shooting the 6.5mm 140 hybrid
and pointed the tips with the widden bullet pointing system.
Still using the G7 BC given by Brian litz .319
And getting good results using the kestrel with AB and the AB-app.

 

[R.Morehouse]

If you have the room take it out to transonic and true it then adjust your program. I use ATRAG MX.. 8)

 

[dcnyli]

i can take it transonic, but was curious if theres other parameters to mess around with in the AB program(iPhone) that would be more direct to this issues.

 

[Bryan Litz Ballistics]

My advice, add 4% to your G7 BC for pointing

so, .319*1.04 = .332

Use this BC for pointed bullets.

The small 4% difference could be 'absorbed' by truing MV; you wouldn't be getting the actual MV, but the offset would introduce very little error in your trajectory predictions until you got way past the true point.

The amount of BC increase you get from pointing depends, but is usually 3-5% so 4% won't be far from reality. Until each bullet is tested pointed vs. unpointed we won't know for sure but 4% is a very good bet.

-Bryan

 

[dcnyli]

thank you very much Bryan! I actually got the die setup from your online shop!

I appreciate the help and your contributions to the shooting community!!

 

[jsthntn247]

I tipped some bullets for the last match and needed just hair less than 1 moa elevation at 600. Appears to be a 6-7% increase.

 

[watercam]

Bryan published some data recently that showed only a 1% increase in BC for the Berger Fullbore bullets. I tested trimmed/pointed bullets against stock and sure enough there was very little change in overall elevation but the pointed bullets were much more consistent in elevation. Over all elevation was reduced by about 20% compared to non-pointed. So, even though I theoretically don't need to, I definitely trim and point!

 

[jsthntn247]

I actually lost bc and consistency when I trimmed. I now just point only.

 

[dcnyli]

I saw about .4mil improvement at 1300yds, my kestrel AB with the .332 was dead nuts accurate, didn't have to true anything