Build spin drift into scope?

How many guys here build spin drift into their scope via shooting slightly left during tall target test?

Mram10us said:

How many guys here build spin drift into their scope via shooting slightly left during tall target test?

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How much spin drift do you figure there is at 100 yards?

Slightly left for tall target test then verify at 500+ on calm day

Nope. Just call the wind.

Slightly left isn't enough precision for what it will equate to at distances spin drift matters. You'd be better off just trusting unverified output from your calculator, or even better don't calculate spin at all. Just let it go for less than 1500.

if you wanted to test it then you'd want to shoot a known distance target (paper) on a calm morning. Make no wind adjustment and shoot a group, then measure average. Verify it with calculator and add to dope book. My opinion is a good test distance is around 600.

Spin drift for most common combinations equates to about 1% of the drop.

Most ballistic calculators over estimate it. They don't custom calculate it for your individual bullet, twist and velocity.

1% isn't an exact number either, but it is closer than what most calculators put out.

My 7x300 drifts .5 moa at 1000, it's not something you want to overlook considering it accounts for half of a normal kill zone at 1000. Before I started shooting past 500 I would zero my windage at 500, basically figuring that it was more important to have that right at 500 than 100, hitting less than an inch left at 100 rarely matters when hunting big game.
Now I just zero everything at 100 and calculate from there. I always thought left twist barrels made more sense so that coriolis and spin weren't working in the same direction and compounding problems that many dont account for. Not that that would solve a problem, but at least they wouldn't be working together.
Makes sense to me if your shooting less than 800 and just want to take that part out of the equation, you can't really get away with much if you plan on shooting past that and need the math to make the shot.....or a little luck.

nmbarta said:

My 7x300 drifts .5 moa at 1000, it's not something you want to overlook considering it accounts for half of a normal kill zone at 1000.

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Out of curiosity, what is your drop at 1000? About 23 or 24 moa?

Depends on the day, and where I'm at, but with a 100 yard zero I'm almost always between 19 and 20 moa.

I understand the concept of spin drift and the values for each rifle. I'm just curious how many people take it out of the equation. At 1000 yds with my rum and 225s it is 4". That is noticeable. I'd rather be .4" left at 100 than compound issues at 1000

Mram10us said:

I understand the concept of spin drift and the values for each rifle. I'm just curious how many people take it out of the equation. At 1000 yds with my rum and 225s it is 4". That is noticeable. I'd rather be .4" left at 100 than compound issues at 1000

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Maybe I'm missing something. As far as I know, a tall target test is to check scope tracking. What does that have to do with anything else but actual click values and return to zero?

My experience is similar to above. 3-5 inches at 1000 yds, and I can't observe it inside 500-600 yds. I normally just make sure my 100 yd sight in hits slightly left of center (.2-.3 moa) and call it good unless I'm shooting over 1000 yds.

The problem I see is how do you know that it's .4 inches left and just not a zero issue at 100y from any amount of variables?
If you're not into sacrificing 4 inches at a 1000y which I can totally get behind, why not just measure the spin at distance.

Some bullets don't even fully stabilize at 100 yards yet..

Totally agree measuring the spin at 1000. You do a tall target test at 100 then verify further out. Pretty easy to tell if your groups are .5moa left at 100