flight trajectory of Berger 130 VLD?

[jdefranc938]

Hey all,
I'm using the Berger VLD 130gr for my 6.5x47L and I'm having issues with the trajectory. My drop charts are all extremely accurate with matchkings and accubonds but with the berger's, I am hitting about 6 inches high at 300 yards when I dial in the elevation. The program I use for my drop charts is Ballistic TFE. Like I said, this has been EXTREMELY accurate up until now. Any input on why this is happening?

 

[SBruce]

I'm not sure I am fully understanding your question.....Is 300 yds the furthest you are shooting?

Are you saying that with a 100 zero, the bullets hits 6" high at 300, and the other loads when zero'd at 100 are spot on at 300?

Velocity, Sight height above bore, and True zero distance are the 3 big inputs for POI at 300 yds.
All the other parameters can be off some and you should still be close at 300 so long at those 3 are correct.

 

[6.5shaggy]

I shoot a 6.5-284 and had the same issues when I switched from A-Max to VLD in 140s. I use JBM Ballistics and had to enter a velocity 200 fps faster than chronoed velocity to match actual field drops. I feel that Bergers have hidger bc than published. Try entering the G7 bc and see if that helps. Good luck.

 

[SBruce]

The G1 BC is .612 vs the G7 BC of .313 (according to the numbers in Exbal).

If the program is not designed to accept the G7 BC then the result will be false, and we would shoot high. According to my program it would only result in 3" higher POI at 300 though.?

Using a program designed to accept G7 there is no difference whatsoever until we get out to 800 yds, and then it's only a couple tenth's of an inch on the target (less than the diameter of the bullet).

 

[jdefranc938]

Thanks for the info. The zero on the rifle is at 100. The sight height is 1.5 and the velocity is 2694. The reason I chose 300 today is because I've been missing a lot of ground hogs in the 300-400 yard range since I switched to the bergers. And with it being 6 inches higher than my dialed in correction, now I can see why I have been missing them!

 

[SBruce]

Thanks for the info. The zero on the rifle is at 100. The sight height is 1.5 and the velocity is 2694. The reason I chose 300 today is because I've been missing a lot of ground hogs in the 300-400 yard range since I switched to the bergers. And with it being 6 inches higher than my dialed in correction, now I can see why I have been missing them!

Yea, that would explain a miss. Are you actually still zero'd at 100 with the Berger load? How's your group size at both 100 and at 300?

My program says with a "dead nuts zero" at 100, you should hit about 13" low at 300 without moving the scope adjustments at all.......? I used your velocity and the G1 BC.

Problem with 100 yd zero's is : Are we really exactly dead on at 100.? With a 1.5 sight height, we can be within a 1/2" at 100 and not be truely zero'd until we get out to 150 yds.....something to think about.

Personally, I hate a 100 yd zero. I'll zero at somewhere between 200 and 300 and then let my load tell me the velocity based on shooting drops at 300 and beyond. I trust this more than the cheap chronographs, especially when I can repeat it another day under different conditions. The difference in drop between 300 and 400 yds is a really good indicator of what your real velocity is. Slight changes in BC's don't have much impact until we get further out.

 

[backwoods83]

You stated your using 130s so your G1 should be .552 but the older 140s said .612 and I saw the newest batch tested with a .640 so the 130s are probably around a .570.

 

[SBruce]

Oops, sorry my mistake. I was giving you data from the 140 bullet.

Re-Running the numbers for 100 yds zero with .552 G1 BC at 2694'/sec and 1.5" sight height:
Exbal gives 14" low at 300 with .552 BC
Exbal gives 13.7" low at 300 with .612 BC
If I increase the altitude from sea level to 5000', it only changes to 13.3" low at 300.

Seeing how changes in BC and even altitude make so little difference at 300 yds.......I'd suspect the issue is velocity and true zero distance.?
Just my .02 cents.