204 Bullet BC

[247sniper]

Hi Guys,

Can anyone please help.

I have had a custom .204 for a few years and have had trouble trying to establish a correct or accurate bullet BC. It's the 39 grain Sierra Blitz King. The manufacturer states a G1 BC of .287 at above 3000 ftps then a different figure through different velocity boundarys. This make it difficult to enter a true BC into a ballistic programe. Calculating my own G1 BC I get a figure of .251.

I was thinking though as this is a boat tail bullet would a G7 BC be better used, if so where can I find the figure for that bullet?

I hope someone can help me out here?

Many thanks

Steve.

 

[A_Gamehog]

It takes 2 chronographs setup to get a true reading yourself. Then you find a BC calculator program here and punch in the numbers.

The first chrony's speed, minus the second chrony's speed , and bullet dia, and weight. Somebody else can chime in but it's a close

calculation to do what you wanted.

This one is what I just described. http://www.jbmballistics.com/cgi-bin/jbmbcv-5.1.cgi

Generic types=

http://gundata.org/ballistic-coefficient-calculator/

http://www.hornady.com/ballistics-resource/ballistics-calculator

 

[JASmith]

You can convert the velocity dependent BC to other forms, including G7 here: http://www.jbmballistics.com/cgi-bin/jbmgfa-5.1.cgi

 

[mshelton]

The Applied Ballistics app for Android allows you to enter in multiple G1 BCs for different speeds if you have an interest in that program.

 

[Ledd Slinger]

I personally use the 'Shooter' app when sighting a new rifle in at various long range targets. Only ever used G1 BCs and it seems to work very well to get me on target so that I can make any fine tuning scope adjustments to center up. But I would never trust any calculator by itself for a long range hunting shot on big game. Calculator alone for varmints? Sure why not, but not on big game. Dont want to risk wounding an animal. A calculator is only a tool to help you PRACTICE on on paper. Actually shooting the distances you want to hit is the only sure fire method of knowing whether or not you can make the shot.

 

[247sniper]

The Applied Ballistics app for Android allows you to enter in multiple G1 BCs for different speeds if you have an interest in that program.

Thanks for that mate, but for a cost of £20, will it offer any more or better results etc then the likes of Strelok Pro or Ballistic AE?


Thanks for your help.

Steve

 

[247sniper]

Thanks for your help and advise so far guys, much appreciated.



Steve

 

[mshelton]

The Applied Ballistics app for Android allows you to enter in multiple G1 BCs for different speeds if you have an interest in that program.

Thanks for that mate, but for a cost of £20, will it offer any more or better results etc then the likes of Strelok Pro or Ballistic AE?


Thanks for your help.

Steve

Nope, math is math.

 

[247sniper]

The Applied Ballistics app for Android allows you to enter in multiple G1 BCs for different speeds if you have an interest in that program.

Thanks for that mate, but for a cost of £20, will it offer any more or better results etc then the likes of Strelok Pro or Ballistic AE?




Thanks for your help.

Steve

Nope, math is math.

Cheers, thanks for that buddy.

 

[Ledd Slinger]

Haven't tried Applied Ballistics, but I have tried Strelok. Wasn't crazy about it. Shooter app is $10 in American currency And Strelok is free. I would much rather pay for Shooter than use any of the other free apps I have tried.

With Shooter, you can input angles for elevation correction by holding your phone at the same angle as your rifle. Once you are close, you lock it in and it gives you the corrected adjustment for the range you are shooting. Same goes for wind corrections. You hold your phome at the azimuth angle of the wind, then input the wind speed and angle and lock it in. Though more for sniper applications, Shooter app will also give you windage corrections for moving targets. you can input the targets speed and angle, get the correction, then add or subtract it from the wind adjustments. All rifles and loads are saved in an archive for quick and easy access too. Correction charts are shown in a quick scroll menu, table, or graph. Im sure other apps can do the same thing, but Shooter is definitely the best app I have personally tried so far.

 

[Ledd Slinger]

Was just doing some reading and it appears that Brian Litz developed both the Shooter app AND the Applied Ballistics app. So I'm sure the Applied Ballistics app is just as nice. I didnt realize that both apps can also input your current weather conditions via GPS using data from the nearest weather station. That's really cool. I'll have to try that

Here are the details on what they both have to offer. http://www.bergerbullets.com/bryan-litz-ballistic-apps/

 

[CatShooter]

Hi Guys,

Can anyone please help.

I have had a custom .204 for a few years and have had trouble trying to establish a correct or accurate bullet BC. It's the 39 grain Sierra Blitz King. The manufacturer states a G1 BC of .287 at above 3000 ftps then a different figure through different velocity boundarys. This make it difficult to enter a true BC into a ballistic programe. Calculating my own G1 BC I get a figure of .251.

I was thinking though as this is a boat tail bullet would a G7 BC be better used, if so where can I find the figure for that bullet?

I hope someone can help me out here?

Many thanks

Steve.

Sierra's BCs are unique to Sierra's ballistic program (Infinity), and do not work with others.

That also applies to most company's BCs,because there is no standard way of getting those numbers.

For example, Hornady's BC for the 224" 53 V-Max is 0.291, and the BC for the Sierra 55 SMK is~271(-ish), but the Sierra shoots flatter and has a higher true BC than the 53 V-Max (by drop tests).

And those itty bitty "boat tails" do nothing - those bullets are G-1's... you need a BIG, LONG boat tail to get even close to a G-7.

Buy a copy of Infinity, and you will be able to drop those 39gr SMKs into a soup can at 500 yards.