20moa base, adjusting for scope line of sight

[xxtavixx]

Hello all,

Hoping for an opinion here. Ive got a set up that i use for units where shots are on the long side, historically ive been displeased with my ballistic turret having elevation stop at 670 yards. I want to practice further, but my range has 600 or 850. The holdover is such that i cannot see the target at 850 with my elevation maxed out.

I installed a 20moa base. My scope was originally zero'd at 200 yards using a zero stop, giving me elevation to 670.

As i understood the 20moa base, it would point the scope down ward, or raise the barrel relative to scope (depending on your perspective). If you shot a laser, youd adjust by moving the scope 20moa. But if you shot a laser you wouldnt need the 20moa base.

Where i am struggling is establishing an understanding of what my new "zero" is based off 20moa base being added. I did talk to someone i considered to be an expert and they advice my new zero would be 400-425 yards as is, i just dont understand how they got to that.

I know I can just go shoot, but im now worried that i dont have enough elevation to set a reasonable zero once i realized my scope has less elevation than i expected, 55 clicks at 1/4 moa. Getting to a range with the needed distance is a commitment for me, so i try to set myself up for success before commuting there.

Load:
160g
.531 g1
3000fps
Sea level

Thank you for helping me understand!

 

[cohunt]

This just made me think about a new question relating to 20 moa rails.

Is there a place to input your moa offset in the streelok app? I'd imagine it t would change your poa and drops

I found an "moa offset" place I'm streelok-- I'm making myself sound dumb as I'm sure if o sat down I could figure it out-- but would a 20moa rail be a + or - offset?

 

[Texanjohn]

When you dialed 20 min what yardage were you shooting? That's should be where your rifle is now"zeroed" but shoot and zero it at you normal 100 yard zero and you should now have 20 min more adjustment, hope this helps

 

[xxtavixx]

That logic works if shooting a laser. Accounting for bullet drop, its gonna be quite a bit different. This is also part of my learning curve, I did not realize by moving to the Swarovski ballistic turret. I would lose so much elevation. I went from 43moa of clicks to 13.5 MOA. I cannot move my scope 20moa to do a direct offset at 100 yards

 

[xxtavixx]

This just made me think about a new question relating to 20 moa rails.

Is there a place to input your moa offset in the streelok app? I'd imagine it t would change your poa and drops

I found an "moa offset" place I'm streelok-- I'm making myself sound dumb as I'm sure if o sat down I could figure it out-- but would a 20moa rail be a + or - offset?

I havent found it. I lost strelok because of the sanction, i got a new phone and didnt know about the sanctions removing the app from ios store

 

[marksman1941]

You can't change moa offset in strelok that I know of, but it's not a hard math problem to figure out.

Take any ballistic app you want and input all of your information as you normally would. Set your zero at 200. Look at your drop chart that is output and see where 20 moa lies. That's your new zero. It won't be perfect but it will be very close.

Picture attached as an example. This my .308 with a 200 yard zero. 750 yards on the table is 19.1 moa, and 800 yards is 21.7 moa. So one could safely assume that changing the zero by 20 moa will move it to approximately 765 yards.

 

[Southpaw Tikka]

The offset in that app (I have it as well) is for your zero regardless of range of said zero. To simplify this, say 200 yard zero but the center of your group is .5 in high and .625 left of dead center you would apply those factors in their appropriate locations. That way if you want to shoot at a longer range, i.e. 1000 yards, because your group isn't exactly dead center it will require an adjustment to the right. I hope I made sense

 

[xxtavixx]

You can't change moa offset in strelok that I know of, but it's not a hard math problem to figure out.

Take any ballistic app you want and input all of your information as you normally would. Set your zero at 200. Look at your drop chart that is output and see where 20 moa lies. That's your new zero. It won't be perfect but it will be very close.

Picture attached as an example. This my .308 with a 200 yard zero. 750 yards on the table is 19.1 moa, and 800 yards is 21.7 moa. So one could safely assume that changing the zero by 20 moa will move it to approximately 765 yards.

Thats how i assumed it would be, but i was informed i was wrong. Thats what is confusing me. Its a problem for me now that i realize my scope with the BT now only has 13.5 moa of elevation, i dont think I can reasonably get to even a 500 yard zero if thats correct

 

[cohunt]

Do you need to add/subtract the offset rail in the app? If you zero it at your intended zero range with the 20moa rail already on it--- do you need to add in the rail offset? Since the scope works like a laser, but the bullet acts like a rainbow won't they still converge correctly?

Other place to add the offset/rainbow would be in the "scope/shooting angle" wouldn't it?

I'm just trying to comprehend how a scope pointed 20moa down would correspond to the rifle pointing 20moa up (since it's really the angle of the rifle you are changing not the scope- since the scope always points "straight" to the target you are actually tricking yourself to just point the rifle higher

 

[marksman1941]

Do you need to add/subtract the offset rail in the app? If you zero it at your intended zero range with the 20moa rail already on it--- do you need to add in the rail offset? Since the scope works like a laser, but the bullet acts like a rainbow won't they still converge correctly?

Other place to add the offset/rainbow would be in the "scope/shooting angle" wouldn't it?

I'm just trying to comprehend how a scope pointed 20moa down would correspond to the rifle pointing 20moa up (since it's really the angle of the rifle you are changing not the scope- since the scope always points "straight" to the target you are actually tricking yourself to just point the rifle higher

Edit - I meant to reply to the post above this but can't figure out how to change which quote is in here

20 moa is 20 moa no matter how you get it. A canted base, shimmed rings, a turret or a reticle offering a 20 moa adjustment will all move POI to the same place (within reason). A 20 moa base is equal to adjusting your turret up 20 moa.

I have a rem 700 in .308 with a vortex strikefire 5-25 on it. That scope has 110 moa of vertical adjustment. When I set up my optic with a standard rail and rings, my 100yd zero was roughly in the middle of the adjustment range. That didn't give me enough turret to shoot as far as I wanted. So I put on a 20 moa base and Burris XTR rings which are shimmed and added 40 more moa for 60 moa total adjustment just in rings and base. After that install, I had to screw my turret down 60 moa, to nearly the very bottom of the scopes adjustment range (about 3 moa off the bottom) in order to zero at 100 yards. And that gave me 117 moa of vertical adjustment to use when playing range games.

 

[Shane Lindsey]

OP, you may/may not have enough elevation in your turrets. 1" scope tube?

I had this issue with a Savage Flat Back. I was running out of elevation before I could even zero the rifle. I can only use a 0 MOA rail, however I used the Burris XTR Signature rings and it was able to correct it to give me enough elavation back. They have different MOA inserts that can help. They are heavy rings, but may be worth a look. https://www.burrisoptics.com/mounting-systems/xtr-signature-rings

 

[cohunt]

Edit - I meant to reply to the post above this but can't figure out how to change which quote is in here

20 moa is 20 moa no matter how you get it. A canted base, shimmed rings, a turret or a reticle offering a 20 moa adjustment will all move POI to the same place (within reason). A 20 moa base is equal to adjusting your turret up 20 moa.

I have a rem 700 in .308 with a vortex strikefire 5-25 on it. That scope has 110 moa of vertical adjustment. When I set up my optic with a standard rail and rings, my 100yd zero was roughly in the middle of the adjustment range. That didn't give me enough turret to shoot as far as I wanted. So I put on a 20 moa base and Burris XTR rings which are shimmed and added 40 more moa for 60 moa total adjustment just in rings and base. After that install, I had to screw my turret down 60 moa, to nearly the very bottom of the scopes adjustment range (about 3 moa off the bottom) in order to zero at 100 yards. And that gave me 117 moa of vertical adjustment to use when playing range games.

Perfect, thanks--- that's what I was leaning towards--- but I also know when shooting uphill or downhill, your drops are not as extreme as when shooting level--- so I had my head wrapped around the wrong thought process.
With a 20moa rail your barrel is still pointed the same way to hit at your zero-- you are just "tricking your brain" by changing your scope settings---- got it.

Well- I'm tricking my brain anyway

 

[xxtavixx]

OP, you may/may not have enough elevation in your turrets. 1" scope tube?

I had this issue with a Savage Flat Back. I was running out of elevation before I could even zero the rifle. I can only use a 0 MOA rail, however I used the Burris XTR Signature rings and it was able to correct it to give me enough elavation back. They have different MOA inserts that can help. They are heavy rings, but may be worth a look. https://www.burrisoptics.com/mounting-systems/xtr-signature-rings

You got it. Thats the discovery im having. Savage round for me, swarovski z5

 

[marksman1941]

Perfect, thanks--- that's what I was leaning towards--- but I also know when shooting uphill or downhill, your drops are not as extreme as when shooting level--- so I had my head wrapped around the wrong thought process.
With a 20moa rail your barrel is still pointed the same way to hit at your zero-- you are just "tricking your brain" by changing your scope settings---- got it.

Well you're not tricking anything really. The scope alignment to bore relationship is what dictates your point of impact. The closer to parallel the relationship, the lower the bullet will impact. The closer to perpendicular the relationship (clearly never nearly perpendicular, but you are technically adjusting in that direction) the higher the bullet will arc, which will give you the ability to aim your scope at your desired point of impact at further distances. There's no tricking your brain of anything, though. It's just the math of that relationship.

Regarding angled shots, you're right in that drops aren't as extreme as shooting level. Weird as it sounds, the bullet only "cares" about the horizontal distance. Most modern range finders have an angle adjustment function that will tell you the distance to adjust/shoot for, instead of the actual linear visual distance. The more extreme the angle the more pronounced this effect becomes, both uphill and down. People tend to aim too high on uphill and low on downhill shots expecting gravity to pull the bullet downward, but that's not how it works.