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d_striker
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Posted: 2/17/2011 11:53:45 AM
[Last Edit: 2/17/2011 11:54:41 AM by d_striker]
Which model should I select for my ballistic calculator app? The difference in drop is pretty drastic between the two models.

I use or plan on using the following bullets. They are all boat tails.

175 SMK
165/180 Sierra Gameking SBT
165/180 Nosler Accubond
300BR
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Posted: 2/17/2011 1:06:24 PM
I pay more attention to G1 vs. G7 after 1500 yds., but I shoot a fairly flat cartridge. If you 're shooting to the point where the two diverge, use the G7, otherwise don't sweat it. You should be confirming your ballistics card with range data anyway.

John
Juice5610
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Posted: 2/17/2011 1:23:35 PM
G7 and make sure you enter the G7 BC. Feom my understanding G1 was designed for handgun bullets and was the standard for years. G7 IS FOR RIFLE BULLETS


Here are the G7 BC's of the most common bullets we use in competition.

Lapua 0.308" 155gr Scenar 0.236
Sierra 0.308" 155gr Palma 0.229
Hornady 0.308" 155gr Amax 0.212
Hornady 0.308" 168gr Amax 0.230
Sierra 0.308" 168gr Matchking 0.218
Nosler 0.308" 168gr Competition 0.218
Sierra 0.308" 175gr Matchking 0.243
Hornady 0.308" 178gr Amax 0.240
Sierra 0.308" 190gr Matchking 0.270
Hornady 0.308" 208gr Amax 0.324

Berger 0.284" 180gr VLD 0.337
Sierra 0.284" 175gr Matchking 0.327
Hornady 0.284" 162gr Amax 0.307

Sierra 0.264" 142gr Matchking 0.301
JLK 0.264" 140gr VLD 0.327
Berger 0.264" 140gr VLD 0.313
Hornady 0.264" 140gr Amax 0.299
Nosler 0.264" 140gr Competition 0.281
Lapua 0.264" 139gr Scenar 0.285
Berger 0.264" 130gr VLD 0.282
Sierra 0.264" 123gr Matchking 0.260

Berger 0.243" 115gr VLD 0.279
Tubb 0.243" 115gr Dtac 0.276
Sierra 0.243" 107gr Matchking Use 0.510 G1 bc

Sierra 0.224" 69gr Matchking 0.169
Berger 0.224" 75gr VLD 0.217
Hornady 0.224" 75gr Amax 0.212
Sierra 0.224" 77gr Matchking 0.190
Berger 0.224" 80gr VLD 0.228
Sierra 0.224" 80gr Matchking 0.217
Berger 0.224" 90gr VLD 0.281
Juice5610
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Posted: 2/17/2011 1:29:58 PM
Sign up. The info that can be found our forum is priceless

The above is taken from this thread. Brian Litz of berger bullets is a genius!!
http://caprc.com/forums/viewtopic.php?f=9&t=987
d_striker
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Posted: 2/17/2011 1:49:25 PM
[Last Edit: 2/17/2011 1:56:36 PM by d_striker]
Originally Posted By 300BR:
I pay more attention to G1 vs. G7 after 1500 yds., but I shoot a fairly flat cartridge. If you 're shooting to the point where the two diverge, use the G7, otherwise don't sweat it. You should be confirming your ballistics card with range data anyway.

John


I'm shooting .308. The difference in drop is anywhere from 1"-4" depending on distance.

What you say is true about confirming with range data, but the closer I can get my ballistic data to my actual range data from the start, the less work I have in the end.

d_striker
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Posted: 2/17/2011 1:49:55 PM
Originally Posted By Juice5610:
Sign up. The info that can be found our forum is priceless

The above is taken from this thread. Brian Litz of berger bullets is a genius!!
http://caprc.com/forums/viewtopic.php?f=9&t=987


Thanks... Will do.
300BR
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Posted: 2/17/2011 2:15:37 PM
[Last Edit: 2/17/2011 2:16:14 PM by 300BR]
Originally Posted By d_striker:
Originally Posted By 300BR:
I pay more attention to G1 vs. G7 after 1500 yds., but I shoot a fairly flat cartridge. If you 're shooting to the point where the two diverge, use the G7, otherwise don't sweat it. You should be confirming your ballistics card with range data anyway.

John


I'm shooting .308. The difference in drop is anywhere from 1"-4" depending on distance.

What you say is true about confirming with range data, but the closer I can get my ballistic data to my actual range data from the start, the less work I have in the end.



I guess we think different... or you HAVE to make the first shot count with no field data. For most of my shooting if my first, unconfirmed with field data, shot is with in 1-4", I'm delighted.

Bryan Litz's G7 #'s are built into the pull=down bullet menu on JBM, FWIW and have been very close out past 2000 yds. for me.

John
Juice5610
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Posted: 2/17/2011 3:52:38 PM
Originally Posted By 300BR:
Originally Posted By d_striker:
Originally Posted By 300BR:
I pay more attention to G1 vs. G7 after 1500 yds., but I shoot a fairly flat cartridge. If you 're shooting to the point where the two diverge, use the G7, otherwise don't sweat it. You should be confirming your ballistics card with range data anyway.

John


I'm shooting .308. The difference in drop is anywhere from 1"-4" depending on distance.

What you say is true about confirming with range data, but the closer I can get my ballistic data to my actual range data from the start, the less work I have in the end.



I guess we think different... or you HAVE to make the first shot count with no field data. For most of my shooting if my first, unconfirmed with field data, shot is with in 1-4", I'm delighted.

Bryan Litz's G7 #'s are built into the pull=down bullet menu on JBM, FWIW and have been very close out past 2000 yds. for me.

John


He is using either shooter for the android or ballistics fte for the iphone not JBM. JBM is awesome though
ChrisGarrett
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Posted: 2/17/2011 5:42:05 PM
Originally Posted By d_striker:
Which model should I select for my ballistic calculator app? The difference in drop is pretty drastic between the two models.

I use or plan on using the following bullets. They are all boat tails.

175 SMK
165/180 Sierra Gameking SBT
165/180 Nosler Accubond


G7 results are valid over a wide margin of velocites, which mimics a bullets true path to the target.

G1's drag model was for the old artillery shells, which used 'flat base' projecticles IIRC.

G3 I want to say, is for more modern boat tail projectiles.

G7 is the way to go if you have a G7 B.C. for a given projectile, to input.

Bryan Litz has these listed in his book and if you glean the web, you can find out some of them without having to buy his book. Search SnipersHide.

As an example, Hornady's 7mm 162gr AMAX is listed at a G3 of .625, but he's knocked it down to .599, so things vary.

Chris



d_striker
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Posted: 2/17/2011 6:44:52 PM
Originally Posted By Juice5610:

He is using either shooter for the android or ballistics fte for the iphone not JBM. JBM is awesome though


I have Ballistic FTE for iphone.
ziebart
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Posted: 2/19/2011 2:54:42 PM
[Last Edit: 2/19/2011 2:56:25 PM by ziebart]
I just got Ballistic FTE and used the G1 to get me on paper. When I got home I played with the numbers until I got something that matched up. G7 seems to match up the best. Still it is off at a 500 and 800 yards, but on at 600, 700 and 900, 1000. The bc numbers I ended up using were pretty far off from what I had got off the interwebs. It might be due to me not putting in the atmospheric conditions correctly. I can't seem to get the density altitude field to be in feet, it shows up in lb/ft3. I wish there was a manual, FAQ, or at least an explanation of terms like JBM uses.

I was using a 115 DTAC and published G7 is .276 I used .335.
Juice5610
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Posted: 2/19/2011 3:04:03 PM
These are all correct


Here are the G7 BC's of the most common bullets we use in competition.

Lapua 0.308" 155gr Scenar 0.236
Sierra 0.308" 155gr Palma 0.229
Hornady 0.308" 155gr Amax 0.212
Hornady 0.308" 168gr Amax 0.230
Sierra 0.308" 168gr Matchking 0.218
Nosler 0.308" 168gr Competition 0.218
Sierra 0.308" 175gr Matchking 0.243
Hornady 0.308" 178gr Amax 0.240
Sierra 0.308" 190gr Matchking 0.270
Hornady 0.308" 208gr Amax 0.324

Berger 0.284" 180gr VLD 0.337
Sierra 0.284" 175gr Matchking 0.327
Hornady 0.284" 162gr Amax 0.307

Sierra 0.264" 142gr Matchking 0.301
JLK 0.264" 140gr VLD 0.327
Berger 0.264" 140gr VLD 0.313
Hornady 0.264" 140gr Amax 0.299
Nosler 0.264" 140gr Competition 0.281
Lapua 0.264" 139gr Scenar 0.285
Berger 0.264" 130gr VLD 0.282
Sierra 0.264" 123gr Matchking 0.260

Berger 0.243" 115gr VLD 0.279
Tubb 0.243" 115gr Dtac 0.276
Sierra 0.243" 107gr Matchking Use 0.510 G1 bc

Sierra 0.224" 69gr Matchking 0.169
Berger 0.224" 75gr VLD 0.217
Hornady 0.224" 75gr Amax 0.212
Sierra 0.224" 77gr Matchking 0.190
Berger 0.224" 80gr VLD 0.228
Sierra 0.224" 80gr Matchking 0.217
Berger 0.224" 90gr VLD 0.281
Eagle-ReaperDriver
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Posted: 2/19/2011 7:57:32 PM
[Last Edit: 2/19/2011 7:58:30 PM by Eagle-ReaperDriver]
Not to be nit picky, but actually G5 BCs are best for the common boat tail bullets like 175 and 168 SMKs, etc. G7 is for the VLD bullets like the Lapua Scenars, Berger VLDs and the like.

Having said that, I use G7s exclusively for 175 SMK and they are way more accurate in my ballistic calculators than the G1s beyond about 500 yds. Under that, you'll see almost no difference. I've usually been within .1 to .2 mil at 1000 yds with G7s and correct data. But like anything, garbage in/garbage out. If the rest of your info like MV and atmospheric data sucks, your output will also suck.
LoneWolfUSMC
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Posted: 2/20/2011 2:50:54 PM
Originally Posted By Juice5610:
He is using either shooter for the android or ballistics fte for the iphone not JBM. JBM is awesome though


Ballistic FTE uses the JBM Ballistics engine unless you turn it off in settings. So in effect Ballistic is just the user interface for the JBM calculations.

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Juice5610
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Posted: 2/20/2011 3:23:01 PM
True but I've found shooter for the android to be far more accurate as far as first round hits go. Also the guy that designed it is on the hide. One of the shooters in the club I'm in contacted him and had him add a feature we needed/wanted. You cant beat that kind of service.