Rifle Scopes 20 MOA Base 100yd -> 500yd help

[Grantsales]

I new here and this is my first post, so please be nice.
I've googled, and searched existing threads and I'm still confused.

Here is my setup:
Rifle: Remington 700 5R 24" .308 win
Optics: Leupold VX-R Patrol 3-9x
Ammo: Federal Gold Medal Match 175gr Sierra MatchKing (GM308M2)
Mount: 20 MOA picatinny base with 30mm standard rings (.823").

I intend to use this setup for target / fun shooting 100 yards out to maybe 500 yards max. I also intend to hunt deer with different ammo of course, hunting round will be Federal Fusion .308 180gr since the ballistics look like they match closely with the Match ammo I have.

Finally my question:
If I sight in at 100 yards or maybe even 200 yards. How will my 20 MOA base impact my scope MOA adjustments when I want to move my shot out from 100 yards to 500 yards?

The fancy hornady calc seem to tell me that I need to come up 9.9 MOA if I sighted in at 200 yards, but since my scope base is +20 MOA does this mean I'm actually going to be shooting too high and I'll need to drop 10.1 MOA?

This whole angle of the scope base has me pretty confused and I can't seem to find a ballistic clac that takes that into consideration, I wish I wound have just got the flat base for my 100-500 yard gun until I became more of an expert in this stuff.

Any advice, help, or links to a better ballistic clac would be great.

 

[mercracing]

Sight in at 100. The 20 MOA base is is to help dial in longer ranges.


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[Grantsales]

Sight in at 100. The 20 MOA base is is to help dial in longer ranges.


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Thanks for the reply and feedback, but this was only a small part of the question.

If I do sight in at 100 yards, then at 500 yards, I'm looking at a 63" drop. This would convert to about 12 MOA adjustment that would be needed to hit the target, does the 20 MOA base impact this adjustment at all?

 

[LoanHarvey]

Sight that baby in and rock on!

 

[mercracing]

No. Ignore the fact you have the rail. the 20 MOA rail does nothing to your math.


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[LoanHarvey]

+1, ignore the 20MOA base. Sight In and Shoot that Mother!

No. Ignore the fact you have the rail. the 20 MOA rail does nothing to your math.


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[agbm]

Get the 20 MOA base, 0 MOA base would be a waste of money to ge. 20moa base should be fine, looks like the scope you have has 60 moa total elevation. Take half of 60 moa = 30 moa +20 moa base = 50 moa total elevation up and 10 elevation down. Looking down the road 50 MOA will get you way past 1000 yards. Now just have fun

 

[agbm]

Thanks for the reply and feedback, but this was only a small part of the question.

If I do sight in at 100 yards, then at 500 yards, I'm looking at a 63" drop. This would convert to about 12 MOA adjustment that would be needed to hit the target, does the 20 MOA base impact this adjustment at all?

Correct, base does not effect impact.

 

[fw707]

Just do it like Ron Popeil's Ronco Rotisserie.....

Set it, and forget it!

 

[92trk]

No it does not.

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[Grantsales]

Could someone perhaps explain this in more detail?

I'm pretty confused on how the 20 MOA base has no impact on the after zero adjustment (sight in at 100, but shooting at 200 / 300 / 400)

Like I said, I'm new here, but can't seem to figure out the answers on my own and need some help.

Everything that I've been taught so far is that the flight of the bullet is relatively flat for at least the first 100 yards. The cause of the bullet drop is due to gravity and this is where velocity and ballistic coefficient come into play to retain the speed.

If my scope is level with my barrel (0 MOA base) and I sighted in at 100 yards, now I'm about to shoot at 200, I'd expect my point of impact to be 4.4" below where I had sighted in my rifle. Solution here would be to shoot 4.4" above my target or simply adjust the dials on my scope to bring the ridicule down 4.4" or 2.1 MOA.

All of this makes sense to me since my scope is level with my barrel.

What doesn't make sense to me is that if the scope is mounted at a slight slant in comparison to the barrel, and now I sight in at 100 yards. Anything I look at through my scope that isn't at 100 yards, for example 200 yards, my scope is already pointing slightly lower on that target then if I would have had a flat base.



So my point of confusion is if I sight in at 100 yards with a 20 MOA base in one rifle and a flat base in another. Now go out to 200 yards, is the 2.1 MOA adjustment the same on both rigs to hit the target?


I'm not sure why this isn't making sense to me I'm sure I'm way over thinking this to my disadvantage.

 

[chopiesel]

You're on the right track,

Imagine with a 0 moa base your scope from zero has 30 moa up and 30 moa down adjustment.

Ad a 20moa base you will now get 50 moa up and 10 moa down. That's the best way I can describe it.

 

[Grantsales]

The reason this isn't making sense to me is that I always thought 1 MOA is 1" at 100 yards.

So in theory. If i sight a scope in on a flat base at 100 yards.

Now put that scope on the same gun with a 20 MOA base, i'll be shooting 20" too high at the same 100 yards.

Move this out to 200 yards and I'd be 40" higher minus the 4.4" of extra drop so maybe really at 35.6" off. And if I needed to make a 2.2 MOA adjustment since my scope is already angled down further, 1 MOA may not actually equal 1" at 100 yards when my scope isn't mounted flat.

Obviously I will not be sighting in a scope on a flat base then remounting it and using it. I'm just trying to explain the incomplete thoughts in my brain that is causing me confusion and making me think I'm going crazy.

 

[chopiesel]

Your scope doesn't know it isn't mounted parallel to your bore

Once you zero it at 100 with the 20moa base it's business as usual.
But you will now be able to dial out to distances you couldn't with the flat base.

 

[Big Bronze Rim]

You would be 20" high at 100 if you didn't zero the scope. You are forgetting that you now have to dial the optic down to zero at 100. This now gives you 20MOA more up adjustment from your optic that would have been otherwise wasted. Just zero at 100 and drive on.

 

[oldfatguy]

The reason this isn't making sense to me is that I always thought 1 MOA is 1" at 100 yards.

1 MOA may not actually equal 1" at 100 yards when my scope isn't mounted flat. .

One MOA is 1.047" at 100 yds, not that it really matters. As had already been said, mount the scope, zero at 100 yds and stop over thinking.

OFG

 

[Eblade2004]

The reason we use a 20 moa base is to get better use of the internal adjustment in the scope. If from top of adjustment to bottom you have say 26 mils of adjustment in your scope, if you use a 0 moa base in theory you should be near the center of the mechanical adjustment in the scope when your rifle I zeroed. Which would leave you with the ability to use only 13 mils to dial a shot before you bottom out. By using a 20 moa base you gain yourself some adjustment by tilting the scope and zeroing off center in the adjustment range of the scope, which will add about 5.8 mils at 100 yards gaining you almost 50% more adjustment with that scope. Set it and forget it, zero is zero. You never have to factor in the 20 moa again.

 

[alpine44]

Don't forget that if you would change from a 0 MOA base to a 20 MOA base you would have to crank the scope 20 MOA down to reestablish zero (assuming that the base is exactly machined and would not change the windage). After reestablishing zero, the 20 MOA base will not influence anything anymore. All it did was to shift the mechanical center of your scope by 20 MOA.

 

[Pinecone]

You are not seeing, that even with the 20 MOA base, when you zero at 100 yards, the OPTICAL axis of the scope is now closely aligned with the bore.

Therefore, your line of sight is aligned, so when you move out to 200 yards or further, you still adjust the OPTICAL alignment of the scope to be a higher point of aim.

Ignore the scope tube.

 

[Grantsales]

Thanks for the responses, this is starting to sink in better.

. . . . now to find a range that will let me shoot over 100 yards in Minnesota

 

[Nik H]

I could have this all wrong since I never used a base with a tilt. However, maybe you can look at it this way.

When you are complete with the zeroing process your elevation knob will be in a different position with respect to center when using a 20 mil base versus a 0 mil base. That is why a base with a cant allows you to shoot at longer ranges.

Hope I am right

 

[wielywilly-g]

The reason this isn't making sense to me is that I always thought 1 MOA is 1" at 100 yards.

So in theory. If i sight a scope in on a flat base at 100 yards.

Now put that scope on the same gun with a 20 MOA base, i'll be shooting 20" too high at the same 100 yards.

Move this out to 200 yards and I'd be 40" higher minus the 4.4" of extra drop so maybe really at 35.6" off. And if I needed to make a 2.2 MOA adjustment since my scope is already angled down further, 1 MOA may not actually equal 1" at 100 yards when my scope isn't mounted flat.

Obviously I will not be sighting in a scope on a flat base then remounting it and using it. I'm just trying to explain the incomplete thoughts in my brain that is causing me confusion and making me think I'm going crazy.

Maybe you could use a visual analogy using a flashlight and a garden hose.

Think of your barrel as a garden hose.
Consider your bullet path as the water squirting from the end.
Think of your scope as a flashlight
Consider your scope adjustment area as the beam of the flashlight.
If you mount the flashlight parallel to the hose, only the bottom part of the flashlight beam will hit the squirting water.
Tilt the light down and it will encompass more of the water stream. That is what we want, more of the bullet’s path in the scopes adjustment range.
I my opinion, no bases should be zero degrees. At a minimum they should be 5 minutes of angle. For Modern scopes, most should be 0.66 degrees or 40 MOA.

 

[Grantsales]

Maybe you could use a visual analogy using a flashlight and a garden hose.

Think of your barrel as a garden hose.
Consider your bullet path as the water squirting from the end.
Think of your scope as a flashlight
Consider your scope adjustment area as the beam of the flashlight.
If you mount the flashlight parallel to the hose, only the bottom part of the flashlight beam will hit the squirting water.
Tilt the light down and it will encompass more of the water stream. That is what we want, more of the bullet’s path in the scopes adjustment range.
I my opinion, no bases should be zero degrees. At a minimum they should be 5 minutes of angle. For Modern scopes, most should be 0.66 degrees or 40 MOA.

I like this analogy, thanks!

It's starting to sink in