wind drift w/ comparable bc question

[gemmellsc]

Trying to get my head around BCs and Wind drift.

Hypothetically speaking if you have a 105gr 6mm bullet w/ a BC of .500 leaving the muzzle at 3000fps and a 180gr .308 bullet w/ a BC of .500 leaving the muzzle at 3000fps both sighted in exactly the same do they:

1.) Drift the same in the wind?

2.) Have the same drop over distance?

Would the only difference be remaining energy at target are does the heavier bullet perform better in the wind and drop less? I read an article in Shooting Times where the author seemed to indicate that this was the case. I thought that equal BC numbers indicated identical flight paths.

Thanks,
Bill

 

[CPorter]

According to JBM, same BC means same trajectory/wind deflection


http://www.eskimo.com/~jbm/cgi-bin/jbmtraj-5.0.cgi

 

[Cheechako]

Bill

It's wind deflection, not drift. But yes, the deflection is the same for both bullets if the BC and MV are the same.

Drift is due to rotation of the bullet and could be different unless the twist is the same for both bullets. Drift is very noticable at the long distances but not so much at short distances. Most ballistic programs do not calculate drift.

Ray

 

[gemmellsc]

Thanks guys. That helps eliminate one of the variables. I've got a Savage w/ McMillan stock and .473 bolt face that I'm going to re-barrel soon. I'm trying to find a cartridge that's a 'do it all' tactical/pratical that can be used for bean field deer/hog/coyote hunting as well. I live in the southeast so the deer aren't too large. I've contimplated everything from just single loading a 6BR to 7SAUM repeater... Too many choices!!! I want something that will push a .500 BC or higher bullet around 3000 fps w/ decent barrel life and enough energy out to 600 yards to do the job, but something that won't rip my shoulder off. I'm not embarassed to say I'm a little recoil shy, and don't really enjoy the .30s. I used to shoot a .300 Win Mag w/ a BOSS, and it took me forever to get rid of my flinch!!!

Any suggestions? Here are the cartridges I am considering.

-6BR single shot using 105gr VLD,alread have a 6BR bench gun and equipment)
-6x47 repeater using 105gr VLD or 115gr VLD
-.243 repeater using 105gr VLD or 115 VLD
-6.5x47 repeater using 130gr VLD
-6.5x284 repeater using 140gr VLD
-7SAUM repeater using 140gr VLD or 168gr VLD

Not saying I have to use the VLD just using them for comparison.

Thanks,
Bill

 

[TonyR]

Hi Bill.
You might want to add the 6.5X55 Swede to your list. I have been thinking along the same lines for a 600 yard gun and it is a very interesting alternative. There have been a number of posts about it on this site. There is also an Ackley Improved version. The specs for factory ammunition aren't very impressive, but with Lapua brass and a custom bolt gun, people seem to be getting great results.

 

[gemmellsc]

Thanks Tony. I've read a little about the Swede, but I've never looked into the AI version. I'll check it out. I love the 6BR... keep wanting it to do the job, but a 6.5 is probably better suited for the bill.