Ballistic Coeff. question.

stovepipe · Posted: Mon Sep 21, 2009 11:03 am Post subject: Ballistic Coeff. question.

I'll admitit. I aint that bright and.... I do not know the BC of my 200gr and 240gr Nos JHP.

If anyone and supply me with that info, or how to find out that info, I'd appreciate it and be a little more enlightened as I wanna play with some recipe numbers and bullet drop with a couple of recipe's.

Thanks,

-kevin.

Pumpkinslinger · Posted: Mon Sep 21, 2009 11:13 am Post subject: Re: Ballistic Coeff. question.

Assuming you're talking about the 0.429" diameter bullets, my Nosler manual Number Three says:

200 grain JHP BC = .151

240 grain JHP BC = .173

stovepipe · Posted: Mon Sep 21, 2009 11:16 am Post subject: Re: Ballistic Coeff. question.

Mikee to the rescue again!

I knew you'd have it.

Thank, bud.

-k.

DallanC · Site Admin Joined: Jan 18, 2005 Posts: 3572 Location: Utah

If you know the muzzle velocity, and the 100 yard velocity, its not hard to compute the BC. Most people accept the "book" values but sometimes its useful to check those at times.

-DallanC

stovepipe · Posted: Mon Sep 21, 2009 11:47 am Post subject: Re: Ballistic Coeff. question.

Thanks D, I really don't know too much on how to calculate that stuff is my main problem.

The Point Blank thing we have here is really neat and something new or me. What a cool deal that is!

SwampFox · Posted: Mon Sep 21, 2009 1:33 pm Post subject: Re: Ballistic Coeff. question.

One thing to watch when you take a BC from a Mfg's data is to check that data against another mfg. The marketing boys tend to play games with the BC numbers for their company. They know people check performance against computer programs and the base of the performance at distance is the BC.
Best,
Ed

stovepipe · Posted: Mon Sep 21, 2009 1:41 pm Post subject: Re: Ballistic Coeff. question.

Thanks Ed, good to know.

Pop's has a lot of manuals and I'm going to go over there and do some resraching and stuff, see what he has on the subject. ... been too busy of late to get over there and I really should be learning more about this now that Boomer's done.

Good info guys, keep it coming.

chambered221 · Posted: Mon Sep 21, 2009 5:11 pm Post subject: Re: Ballistic Coeff. question.

Not that it pertains to handguns but longrange shooters often quote multiple B.C. figures at, below or above a given velocity.
For example: the Sierra 107gr. .243 bullet that is typically used in a 6BR from 600-1,000 yards will read something like this: BC: .527 @ 2500 fps and above; .522 between 2500 and 1800 fps

Also the only true way to measure B.C. is with 2 known velocities at 2 different distances with one bullet in flight going through a pair of chronographs.

woods · Member Joined: Oct 15, 2005 Posts: 89

www.shootforum.com/for...letdb.html

stovepipe · Posted: Tue Sep 22, 2009 6:15 am Post subject: Re: Ballistic Coeff. question.

Ah- I think I', starting to see the relationship between speed and BC.
Did not know that.

Like I said, stuff to learn.

Thanks gents.

Woods- do the "V" values pertain to a known speed? I'm not sure how to read that.

chambered221 · Posted: Tue Sep 22, 2009 4:19 pm Post subject: Re: Ballistic Coeff. question.

Select a caliber, After the bullet list comes up left click on “velocity 4” in the blue shaded area you’ll have different velocities pop up under “velocity" 1, 2, 3, and maybe 4
You can then read the B.C. for a given velocity spread by looking at “B.C. above” V1, V2, V3, and V4

Note: not all manufactures give all this data!!!

stovepipe · Posted: Wed Sep 23, 2009 6:47 am Post subject: Re: Ballistic Coeff. question.

I clicked the V1 etc...nothing came up. Might be this comp. I'll try my roomates laptop when I get home.

chambered221 · Posted: Wed Sep 23, 2009 7:03 am Post subject: Re: Ballistic Coeff. question.

Click the far right box in the light blue that's labeled "velocity 4"

chambered221 · Posted: Wed Sep 23, 2009 7:10 am Post subject: Re: Ballistic Coeff. question.

Actually clicking any of the "velocity" boxes you can get different data if it's available!!!

stovepipe · Posted: Wed Sep 23, 2009 9:32 am Post subject: Re: Ballistic Coeff. question.

Thank you sir.