Action thread timing Question

[WillyTP]

Just having my first cup….Is this saying 11.4 inches at 600 yds with zero wind?

Yes sir

 

[Gil P.]

Yes sir

I'm only getting .1 mils of spin drift starting at 680 yards. It stays as .1 mils to 1000 yards.

My 308 used to get .2 mils of spin drift at 1000.

 

[Tokay444]

This is on a 6 Dasher with all wind inputs at 0.

Have you shot that to confirm?

 

[DaveTooley]

We can reliably confirm drop. We know spin drift is there but because of other factors it's more difficult to validate. Scope tracking, different bullets, different land and groove configurations, accuracy of the ballistic program in this area etc. etc.

 

[dnellans]

Something is wrong with the post that says spin drift is 11 inches at 600. it should be more like 2 inches for any 6mm bullet

 

[dnellans]

To add to list on action timing - Borden does not guarantee it, Impact does, Surgeon does not.

 

[WillyTP]

Have you shot that to confirm?

How? In the 600 yard vacuum range you mentioned earlier? It’s ballistic software, how could it be wrong? That’s a joke before you flip out. Do I personally believe it’s that severe, nope. But it is there and the further you shoot, the more it exists.

 

[WillyTP]

Something is wrong with the post that says spin drift is 11 inches at 600. it should be more like 2 inches for any 6mm bullet

Really? You think a 62 grain flat base is the same as a 109 grain boat tail?

 

[Chaotik]

I am confused. Are we talking about spin drift OR bullet drop at 600 yards. I always thought that these were completely different, but I could be wrong.

 

[dnellans]

Really? You think a 62 grain flat base is the same as a 109 grain boat tail?

they’re not the same, spin drift affects shorter bullets less than longer. the drift on a 62 flat back is less than a 109 BT, not more.

 

[dnellans]

I am confused. Are we talking about spin drift OR bullet drop at 600 yards. I always thought that these were completely different, but I could be wrong.

you’re not wrong

 

[DaveTooley]

I like Hornady's 4DOF. Simple to use and for me has been accurate. For a 6MM 90 gr bullet at 3100 FPS zero wind it gives .3 MOA hold for a RH 8 twist barrel. That's 1.8 MOA of total spin drift @600. Seems about right.

 

[dnellans]

How does a .3 moa hold for no wind translate into 1.8 moa? We must be not using the same terminology somewhere here.

edit - assuming you typo’d and meant 1.8 inches. 600*1.04*.3 = 1.87 inches

agree that’s right on

 

[DaveTooley]

How does a .3 moa hold for no wind translate into 1.8 moa? We must be not using the same terminology somewhere here.

edit - assuming you typo’d and meant 1.8 inches. 600*1.04*.3 = 1.87 inches

agree that’s right on

.3MOA X 6= 1.8 MOA total drift @600

 

[dnellans]

.3MOA X 6= 1.8 MOA total drift @600

That’s not how angular measures (MOA) work and is specified.

.3 MOA at 100 yards is .3 inches, at 600 yards it 1.8 inches. (using 1.0 rather than 1.04)

1.8 moa is 1.8 inches at 100 yards and 10.8 inches at 600.

if you dial .25 moa on your gun and shoot at 600 yards, it won’t move the point of impact 10 inches, it will move it just 1.56 inches.

 

[Gil P.]

That’s not how angular measures (MOA) work and is specified.

.3 MOA at 100 yards is .3 inches, at 600 yards it 1.8 inches. (using 1.0 rather than 1.04)

1.8 moa is 1.8 inches at 100 yards and 10.8 inches at 600.

if you dial .25 moa on your gun and shoot at 600 yards, it won’t move the point of impact 10 inches, it will move it just 1.56 inches.

Dave is making a calculation using a minute of angle and not an approximation. 1.8 MOA is 1.8 MOA, there is no reason to turn it into inches. Using approximations like "1.8 MOA is 1.8 inches at 100 yards" is not true and there's no reason to introduce error, or inches when we are talking MOA.

Inches per hundrer yards turrets should go away too. It seems like they were born due to people comparing moa to inches.

 

[DaveTooley]

I don't understand your fuzzy math. What does your comments about .25 MOA not equaling 10 inches have to do with this conversation? Bizarre
I said the wind drift AT 600 was 1.8 MOA. Emphasis on the 600.
Since you work in inches1.8 MOA = 1.88 inches of total drift measured on the target AT 600 yds .
And yes if I was writing a test evaluation report I would measure the targets and report the number adjusted to 100 yds to facilitate an easy apples to apples comparison.

 

[Tokay444]

1.8MOA doesn't equal 1.88" at 600 yards though.

 

[Gil P.]

1.8MOA doesn't equal 1.88" at 600 yards though.

True lol. He lost me there

 

[DaveTooley]

According to the NSSF.
A Minute of Angle (MOA) is an angular measurement. A MOA is 1/60th of a degree. 1 MOA is a different size at different distances, 8″ at 800 yards is still just 1 MOA.

I agree with that definition. Ballistic program say hold .3 left. The bullet will travel 1.88" right at 600 yds.
I'm and have been talking about group location by doing the math. Dead on at 100 how far does spin drift move the POI at 600. Not by the definition a MOA.