Found this report the other day by accident. It might be of use to some of the Long Range shooters. Measured G7 BC's for Hornady, Sierra, Nosler, & Barnes projectiles.
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Found this report the other day by accident. It might be of use to some of the Long Range shooters. Measured G7 BC's for Hornady, Sierra, Nosler, & Barnes projectiles.
Interesting article. Anyone brave enough to donate their chrony as the 200yd velocity measurement tool :D
Tussock, is your comment in relation to this article, or something else ?Quote:
Originally Posted by Tussock
NOQuote:
Originally Posted by ebf
Just put it up there because it has Bryan Litz's Measured BC's listed. Bergers are absent but at least they put the G7 on the box label. Not sure the authors conversion to G1 using form factors is reliable, and I don't use G1 BC anyway.
Can't see a problem with it but how will you read the numbersQuote:
Originally Posted by ebf
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Loooooong lead for F1 master external display :thumbsup:
I'm nervous enough about hitting the bloody chrony in it is 10ft away. Guess you could make up a nice armour plated box, coz the down range one is going to get dinged a couple of times...
Arnt G7 specific to boat tails??im just learning this shit.
The window is like 12 inch square at least..,I thought we could all shoot 1mm groups at 200 :D
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yea but murphy reckons you "will" put your first round thru the chrony:P
Yep. Been there done that with my first chronograph many years ago. One of those F1 red metal ones with the cardboard sun shades. Found how quickly those little plastic .30 cal sabots deviate from line of bore. They made pretty little star shaped holes in the card board at 5 yards from the muzzle. Lucky no damage to the important bits. I might have a go at 200 or 300 yards when my new Superchrono turns up as I should be able to put it well out of harms way.Quote:
Originally Posted by Neckshot
Tussock, thank you. This is a battle I have fought for years and, after going through the whole explanation, I still get people asking what the (one) BC number for a bullet is. I do not ever mind the question and the explanation, it is the discarding of the explanation that gets to me.
Doesn't Sierra list multiple G1 BC's for their projectiles? I seem to remember Brian Litz saying the advantage of the G7 is that the BC has less variation as the velocity change
Thats what I thought tooQuote:
Originally Posted by Neckshot
No G7's aren't specific to boattails, just that the standard G7 projectile is a boat tail, so a G7 BC is a better fit to boat tails than the G1 BC.
There are other ones as well
Copied from Wikipedia
The resulting drag curve models for several standard projectile shapes or types are referred to as:
G1 or Ingalls (flatbase with 2 caliber (blunt) nose ogive - by far the most popular)[11]
G2 (Aberdeen J projectile)
G5 (short 7.5° boat-tail, 6.19 calibers long tangent ogive)
G6 (flatbase, 6 calibers long secant ogive)
G7 (long 7.5° boat-tail, 10 calibers tangent ogive, preferred by some manufacturers for very-low-drag bullets[12])
G8 (flatbase, 10 calibers long secant ogive)
GL (blunt lead nose)
G1 BC projectile
Attachment 8576
G7 BC projectileAttachment 8577
It is surprising how much the BC changes as the projectile slows down.Quote:
Originally Posted by Tussock
The big 375 projectiles are usually pretty good right out to 2000-2200 yards then it all turns to poos & you need to add more & more, 6moa from memory at 2500 yards, that is quite a bit nearly 4metres, at this stage I only have G1 BCs for them.
I guess the small ones do the same thing if you can be bothered shooting them far enough & can see the strike.
I have better results with Shawn Cs stepped G1 BC over Bryan Ls G7, with the 300 Bergers, there is very little in it until you way out there.
Die G1, die, die, die!
If I understanding the attached paper correctly it compares Litz vs companies, but assuming that Litz did it right?
If one compares Lapua computation (doppler/ measured all along trajectory) with a Litz calculation (estimated/measured at points of the trajectory) one finds discrepancies.
What magnitude of discrepancies? Can you share the comparison?Quote:
Originally Posted by Norway
It dependsQuote:
Originally Posted by Tussock
Yeah. Pretty much. My ignoring certain things at certain ranges isn't unconsidered.Quote:
Originally Posted by Tussock
4-5 clicks
I discovered with 338 DCM in the weekend that I needed to use the G7, mainly I guess because with a muzzle velocity of 3450fps with the 300s, the G7 is a better fit than the stepped G1.Quote:
Originally Posted by Kiwi Greg
Swapping between G7 and G1 BC's on my 7mm RM with 162 Amax does not even account for a single click value out to 800yards on my ballistic app.
Does not seem to make real difference in my particular case until way out there.
G1 1500 yards 45.36 MOA
G7 1500 yards 46.08 MOA
I'm using Ballistic AE which uses the JBM computer and has all Bullet G1 drag models as well as Litz's G7 dataQuote:
Originally Posted by Tussock
Ballistic: The Pro Ballistic Trajectory Computer for the iPhone, iPod Touch, and iPad
