Ballistics program and Bullet B.C. (Long Range Shooting)

[snowshoes22]

I have been shooting long range (0-1550yds) for the last few years. Each year i try to improve my gear and skills. I am currently using Strelok for my ballistic calculations on my smart phone. I really like the program.

Here is my question. Are bullet manufacturers a little on the generous side when it comes to bullet Ballistic Coefficient? All my enviromentals are as close as i can get them and using their numbers the impacts are way off at longer ranges beyond 6 or 700 yards.  I am having to lower the bc's on Amax and SST bullets almost .80 points to get my drops right. My velocities have been confirmed over several chronos. I also shoot berger VLD's but have not noticed such a big difference in my numbers and theirs.

For those who are wondering i am shooting a 6.5 Creedmoor with 140 Amax and a 6.5X284 Norma with 140 Amax and 140 SST for hunting.

Also i am no ballistics expert and do not pretend to be. It is not a big deal but it is always nice to hit where you intend to without a lot of messing around. i just tweak the program untill i get what i want. I am stuck at home today and wish i was out shooting so talking about it is almost as fun.

[Curly]

You might take a look at the link below taken from the jbm online ballistic calculator.  See if you can get a copy of Bryan Litz's book with the G1 and G7 BC's listed for 175 bullets.

http://www.jbmballistics.com/ballistics/calculators/help/common/bclibrary.shtml

[BULLBLASTER]

Do you have devices to get correct environmental information? Pressure and temp? My shooting at long ranges increased drastically when I bought my kestrel. I have heard some companys are generous on published bc... but my bergers shoot spot on to 1k with the bc off the box. I use strlok also.

[snowshoes22]

The bergers have been very close. I am noticing more of a difference with the Hornady bullets. The are very accurate once i get them tuned in with the calculator and $10 less per 100. I need to get a good weather center. Right now i am using a caldwell wind wizard for wind and temp. Pressure i just go generic. The G7 BR2 just arrived 2 days ago and i have only took it out and ranged with it. Not sure what all it does yet. It takes 10 minutes to acclimate for enviroment. The ranging capabilities with it are amazing. I can pick things up better at 1550yds than i can at 500 with my vortex Ranger 1000.

[snowshoes22]

.08 not .80 sorry typo  .8 would be a huge amount

[BULLBLASTER]

.08 is not bad for a discrepency in bc. That g7 rf will tell you everythingnyou need for weather except wind speed. Just learn how to use it.

[snowshoes22]

About 3 moa at 1000 yards

[WoodlandShooter]

I use a modified version of the Pesja EXCELL spreadsheet.

Attached is the opening screen.

I am using Matrix Bullets and Nosler LRABs...I have not had any issues with either.

[BULLBLASTER]

About 3 moa at 1000 yards

Inaccurate weather input will put you off that much or greater. The bc in the program needs to be whatever it needs to be to match the actual trajectory provided all other inputs (atmospheric conditions, velocity, sight height, etc) are accurate regardless of what's on the box.

[WoodlandShooter]

I also learned the hard way that you do not change elevation and BP at the same time. Either Elevation or BP has to be set for a standard, and then vary the other.

so, set BP at 29.92" and leave it. The adjust elevation

or,

set elevation to zero and leave it. Then adjust BP

[BULLBLASTER]

date=1384460968]
I also learned the hard way that you do not change elevation and BP at the same time. Either Elevation or BP has to be set for a standard, and then vary the other.

so, set BP at 29.92" and leave it. The adjust elevation

or,

set elevation to zero and leave it. Then adjust BP
[/quote]
I use actual pressure and leave elevation set at 0.