Moa and bdc?

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Brianma65

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Hello , I have a question about MOA and Bullit drop. If I have a 20 MOA rail on a rifle that's capable of 1 MOA and better , zeroed at 200 yards. And my target is 550 yards away. My Bullit drop is 50 inches. Scope is in 1/4 inch adjustments. So How many clicks will I need to make to allow for the 50 inch drop? Or should I just do some googling :) Scope will be a FFP .and if it's aSFP it should be the same principle as long as the SFP is at max power right? Not that it matters but the 2 scopes I'm looking at are vortex viper pst 6x24 and leupold mark AR mod 1 6x18
 
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Are the clicks in MOA or in IPHY (inch per hundred yards)? There is a difference, and MOA is NOT inches. That little 0.047 difference adds and multiplies at distance when you're dialing.

50 inches at 550 yards is 8.68 MOA or 9.09 IPHY

If you were dialing 40 MOA at 1000 yards:

IPHY: 40 x 1 x 10 = 400"
MOA: 40 x 1.047 x 10 = 419"

The difference is 19". That is a good sized miss!

Whether the scope is FFP or SFP does not affect dialing the turrets. It does matter when you're trying to use the reticle for hold-over instead of dialing the turrets, when you're trying to measure a miss, holding-off for wind or lead a moving target. Then the SFP scope has to be on the correct power (not always maximum, depends on the scope) or you have to multiply or divide your reticle values depending on the power the scope is set on (you also need to verify this because most companies do not calibrate the magnification ring).

You should also zero at 100 yards, not 200. 100 yards is the lowest point on your trajectory from the point of view of dialing the turret. If the target is farther, you dial UP to compensate for bullet drop. If your target is closer than 100 yard, you dial UP to compensate for scope height over bore. With a 100 yard zero, you always dial UP. Zeroing at 200 is something hunters do because they aren't dialing their scopes.
 
Of the 2 scopes I've listed , it didn't say what the click value is, on there website. Or if they're MOA or iphy . I got the 200 yard zero from hornady ballistics as that's all they had for 308. So , zeroed at 100 and one click being 1/4 inch then at 500 yards 1 click equals 1 1/4 inches. So if my trajectory drop is 52 inches that would be 42 clicks right? If I have a iphy scope. I've never heard of a IPHY scope, thought there was only MOA and mil .
 
If you have a 52" drop, you need to add about 10 minutes of elevation, 40 clicks. But don't count clicks. Learn to use your dials, and make your corrections in minutes, and fractions thereof.
Also, ballistic tables are all very well - but you have to learn what your rifle and ammunition do while actually shooting. Keep a record of your "come-ups" for the various distances.
With a known bullet and velocity, a ballistics program will give you really useful starting information. You will get good hits and only need to refine your settings. I have had excellent results using the Sierra program.
What is your bullet and velocity?
 
There are two types of MOA: True MOA (1.047" @ 100 yards) and Shooter MOA (also know as IPHY - 1" @ 100 yards). Most people think you can neglect the 0.047 difference, and in many cases, at short distances and for making small corrections you can. But, when you start shooting out at longer distances, you cannot. That little 0.047 difference is probably the biggest reason why people's come-ups don't match what their ballistic calculator is telling them. Cheap scopes tend to use IPHY adjustments (SMOA), not true MOA (TMOA).

No one talks in clicks. Turrets have numbers on them, so there is no reason to count clicks. 52" at 550 yards will be 9 1/2 MOA or 9 IPHY(or SMOA). If you go to a ballistics calculator like JBM, it will give you your come-ups in MOA, IPHY or mil for your actual set-up. Just plug it in and use it.
 
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Sorry to hijack the thread.
Is it better for an inexperienced shooter to go with a scope that has a target reticle or a BDC reticle?
What I mean is, is it easier to use a bdc than rely on adjusting the turrets?
Myself, I do want to do both, hunt and target shoot with the same gun. Recommended scopes under $800?
Have heard a lot about the Nikon's(Big sky?), vortex, etc.
Bought a Bausch & Lomb 6-24x40 long ago but got it with the wrong reticle. Thinking about a BDC
which would allow for no adjustment time if needing a quick shot.
 
BDC reticles almost never match your actual come-ups. They're fine for hunting but not good for precision work.
 
I'm waiting on a new ruger .308, I'm going to try hornady amax. Not sure which weight yet, maybe 155 g. Maybe some nosler also. Once I find the right cartridge , then I'll work a load up for them. I'm going to do some reading , to learn the technic. I'm not interested in the bdc reticle.
 
Brianma65 said:
I'm waiting on a new ruger .308, I'm going to try hornady amax. Not sure which weight yet, maybe 155 g. Maybe some nosler also. Once I find the right cartridge , then I'll work a load up for them. I'm going to do some reading , to learn the technic. I'm not interested in the bdc reticle.
Click to expand...

I'm using an old ruger M77 in the same caliber. Loved Amax 168's behind 41.5 gr of IMR 4320.
 
TedNugent said:
I'm using an old ruger M77 in the same caliber. Loved Amax 168's behind 41.5 gr of IMR 4320.
Click to expand...
will have to add that to my list. I have to mid September to choose a scope as the gun won't be in Canada until then. I'm thinking a leupold because they tend to be lighter scopes. I'm not exactly getting into the precision game, as of right yet. I just want to learn to use my dials correctly. At least out to 5 or 6 hundred yards . I will be using this out in the bush.
 
TedNugent said:
Sorry to hijack the thread.
Is it better for an inexperienced shooter to go with a scope that has a target reticle or a BDC reticle?
What I mean is, is it easier to use a bdc than rely on adjusting the turrets?
Myself, I do want to do both, hunt and target shoot with the same gun. Recommended scopes under $800?
Have heard a lot about the Nikon's(Big sky?), vortex, etc.
Bought a Bausch & Lomb 6-24x40 long ago but got it with the wrong reticle. Thinking about a BDC
which would allow for no adjustment time if needing a quick shot.
Click to expand...

For target , I prefer turrets, for a little more precision. For big game hunting, I prefer a BDC reticle that is very close to matching the trajectory of the load, because it is quicker to use. Nikon makes good optics for the price, but they do not make a Big Sky.
 
Brianma65...the easiest way to do this is to have a rangefinder that gives drop on MOA and a scope with MOA turrets, read,dial, shoot! :)
 
hawk-i said:
Brianma65...the easiest way to do this is to have a rangefinder that gives drop on MOA and a scope with MOA turrets, read,dial, shoot! :)
Click to expand...
that sounds good. Can you recommend a range finder ? I have a bushnell 1000 , but it's about 6 yes old... Maybe time for a new one.
 
I've never used a scope past 100 yards , shot a couple of moose at 20 yards and sighted in a few rifles at 100. But that's it. Thought I should add that so you know my experience is zero :). I have a rifle ordered that is capable of long range shooting and I'm looking for a scope to suit it. I plan on hunting and target shooting with the same gun. I've watched a couple of vids and read a couple of articles so I'm learning. I guess I have to get the scope and get some practice in. Thanks for the info.
 
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