 NPR2 MOA & holdover? 
04202004, 07:32 AM

Silver Member


Join Date: Jun 2003
Location: Aussie in Italy
Posts: 276


NPR2 MOA & holdover?
I have a question that I basically answer for myself, but I would like to post it and get more input.
My NPR2 reticle has hash marks at 2MOA increments. (2MOA @100yards)
So at a the given 24x setting for this to be relative and true, I thought that at 200yards I should get 4MOA worth of holdover the the first increment, or approx. 12 inches. At 400yards, the frist hash mark down gives me 8 MOA of holdover and so on and so forth.
Right?
I don't think so.
With a 109 yard(100m) zero shooting a .47BC 167gn @ 2686 I should be 11.3MOA low at 500 yards, meaning that I can assume tha bullet strike to be between the 1st and 2nd hash marks. At 11MOA.
What confused me is that the same program that gave me the tradjectory in MOA gives me 59 inches of drop at 500yards.
So without doing any real testing, just by lining up spots 500yards away I see that it looks like that 2MOA mark is 2MOA at all distances.
At 500yards, the first mark down looks like being 10inches, meaning 2MOA.
So I count down 5 hash marks to the 10MOA point, and I have what looks like approx 60inches (4.9ft) go another half hash mark and I am at 11MOA.
Does it sounds like I'm on the right track now?

04202004, 08:36 AM

Platinum Member


Join Date: May 2001
Posts: 2,369


Re: NPR2 MOA & holdover?
Express
MOA in angular measure, doesn't change with distance.
The first hash mark down you said was 2 MOA it subtends, 2" at 100 yards, 4" at 200 yards, 6" at 300 yards... 10" at 500 yards.
The first hash mark down ALWAYS gives 2 MOA, but you're getting to that in your post too.
As you realized, 5 hash marks down is 10 MOA (subtends 50" at 500 yards)

04202004, 08:47 AM

Platinum Member


Join Date: Jun 2001
Location: Palmer, Alaska
Posts: 2,539


Re: NPR2 MOA & holdover?
You're on the right track "now", no worries.
You're right, the 2 MOA does not change with distance, it's value in inches is what is changing.
Two lines diverging at 2 MOA will be 10 times further apart at 1000 yards than they were at 100 yards. It so happens that 1 MOA is approximately 1" at 100 yards so it would be worth 10 times that at 1000 yards, or 10".
1 MOA at 100 yards is worth 1.0472" to be exact, so 11 MOA at 500 yards would be multiplied by 5, then multiplied by 1.047 to determine the inches that 11 MOA is actually compensating for.
If you know the range, and the inches of drop predicted, simply divide to arrive at the MOA needed.
You are on the right track. [img]images/icons/smile.gif[/img]
__________________
Brent Moffitt

04202004, 08:56 AM

Platinum Member


Join Date: Jun 2001
Location: Palmer, Alaska
Posts: 2,539


Re: NPR2 MOA & holdover?
Looks like Dave posted while I was making my coffee. One thing I forgot to add though was, 11 MOA is 5.5 lines down, but also this is why sometimes it is helpfull to zero the rifle at 100 yards higher up above the main crosshair, so at further ranges like 500600 yards you're zeroed with the main crosshair in the center of the tube. You'd be out nerer thedge with 100 yard and 1000 yard zeros instead, but most of your LR shooting would be nearer the middle of optical center.
__________________
Brent Moffitt

05032004, 09:44 PM


Re: NPR2 MOA & holdover?
Shooting a NF NXS, NPR2, 3.5x15x50mm I have a total of 110 (109) MOA of total adjustment. With a 20 MOA base, I am 45.25 MOA up from bottom with a 100 yard Zero; not that far from ocular center. NF NXS
[ 05032004: Message edited by: W ]


Thread Tools 

Display Modes 
Linear Mode


