Bullet drift/spin.

[CK_32]

How do you calculate for bullet spin or bullet drift?

I'm just not shooting past 600 yards with my Remington 700 SPS tactical in 308 and I don't know how to calculate for bullet drift.
And I know it comes into play around those distances. So if anyone could help me out with that it would be much appreciated. Thank you.

 

[Sean P.]

Well I use ballistic software to figure it out but heres the old way if you want it lol

[SamM.]

Spin Drift and Coriolis Drift can play a roll in this. Here is another link to help.
http://www.appliedballisticsllc.com/index_files/SpinandCoriolisDrift.htm

What bullet are you useing ?

[CK_32]

As of right now I'm using cheap 145g FMJ factory loads for brass and get a feel for the rifle. But they are becoming
subsonic and unstable after about 500 yards. I plan on hand loading some 178g SMK loads for 700+ yards and 155g
for anything under 700.

I'm shooting out of a stock Remington 700 SPS tactical. 20" 1:12" twist if your wondering.

[CK_32]

@Sean P.

Yea I'm too cheap and broke for a BC lol
I do all my ranging and math on my I-phone calculator and paper

[Sean P.]

Out to 700 yards with a 1-12 the spin drift is very small probably only about a 1/2 minute.
All I do is add a 1/4 click for anything between 500 and 700 and a 1/2 MOA to about 850 yards.  This is of course if I don't look it up or spend the time to look before I go shooting.  For the most part you don't have to worry about it much unless you start to get to a 1,000+

[CK_32]

Thanks.

I was just told anything after 600 yards spin drift comes into account. Idk how much or much about it in fact.


What about with a 1:10 twist on a 20"?

[Sean P.]

You wouldn't notice the difference unless you where really shooting out there, like 1,500 yards or more and even then it would be a small difference.  Most people will judge the wind a little wrong and it will make much more of a difference down range.  If you could judge the wind very good and didn't know a thing about spin drift you would be shooting better then whole bunch that accounted for spin drift but was so so on reading the wind.

[CK_32]

Haha alright thanks.

BTW I saw your youtube video on using scope. Kinda introduced me to this site.

What caliber in that video are you shooting?

[Sean P.]

30 cal.
I need to start making more videos like that BUT I am not very comfortable in front of the camera yet LOL

[SamM.]

You do fine.

[CK_32]

I feel the same way. My friend want me to do video reviews and i just feel awkward talking to my self and an object.
I can write reviews all day and night but as soon as the camera comes on I'm just like uuhhh.. cut.. haha