Do I need a 20 MOA mount?

nikonNUT

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Evening all. SO I have a question for the optics gurus. I'm running a Vortex Viper PST gen II on my MSR-10 (I know) and I I currently have a 0 MOA mount on a 0 MOA rail. Zeroed at 200 yards I have 15 MRAD of adjustment left. My question is this... I punched the info for the Hornady 140 ELD-M into Strelok and see that at 1400 yards I'm going sub sonic and need 15 MRAD up to get there. Based on this info is there any reason to upgrade to a 20 MOA mount or should I save the money for a Spuhr for my next rifle (Thinking .300 PRC or .338 LM) based on everything petering out at about the same time/distance or did I answer my own question? Thanks for the info and answering a question I'm sure has been asked before (I looked really!)
 
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AIAW

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I have to ask, why a 200 yard zero? You are saving what, .3 MILs? Just complicates things in the long run.

Generally you chose a mount with a forward declination at or under 1/2 of the scopes total mechanical travel in order to give the full range of erector travel. The downside is that optics (lenses) are designed to be used in their center, not at their edges. A slight degradation "could" be noticed when at the ends of travel. Perhaps not enough to matter. I wouldn’t let this be an issue really.

The Vortex Viper PST Gen II has 70 MOA if I am not mistaken. A 30 MOA mount would be perfect.
 

nikonNUT

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I have to ask, why a 200 yard zero? You are saving what, .3 MILs? Just complicates things in the long run.

Generally you chose a mount with a forward declination at or under 1/2 of the scopes total mechanical travel in order to give the full range of erector travel. The downside is that optics (lenses) are designed to be used in their center, not at their edges. A slight degradation "could" be noticed when at the ends of travel. Perhaps not enough to matter. I wouldn’t let this be an issue really.

The Vortex Viper PST Gen II has 70 MOA if I am not mistaken. A 30 MOA mount would be perfect.
I chose 200 simply based on a few ammo makers that give long range ballistics with a 200 yard zero. Looking at Strelok you are correct. Looks like .4 MIL down. I had not considered that the canted base was more to optimize optics performance versus getting the range needed. Looks like I have a Spuhr in my future!
 
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Threadcutter308

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Give some consideration to the fact that rails are less than half the cost of mounts. In other words, if you're going to increase the angle of your scope, personally, I think it's best to buy a 20 MOA rail, as opposed to a 20 MOA mount. More flexibility/resale value for a 0 MOA mount.
 
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nikonNUT

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Give some consideration to the fact that rails are less than half the cost of mounts. In other words, if you're going to increase the angle of your scope, personally, I think it's best to buy a 20 MOA rail, as opposed to a 20 MOA mount. More flexibility/resale value for a 0 MOA mount.
I like this idea! Is there a brand you like? I would adding to an existing picatinny rail...
 

AIAW

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I chose 200 simply based on a few ammo makers that give long range ballistics with a 200 yard zero. Looking at Strelok you are correct. Looks like .4 MIL down. I had not considered that the canted base was more to optimize optics performance versus getting the range needed. Looks like I have a Spuhr in my future!
The "cant" (technically cant is a horizontal aspect - angle or declination is the fancy technically accurate term) is to push the line of sight down into the bore line, so you gain the unused mechanical travel that would have been wasted. Not so much to optimize any optical qualities of any sort. For the scope, down is actually up - it gets confusing without really diving into the internal workings and such.

1575782246998.jpeg

If anything, the extra declination degrades optical quality - but that’s an entirely different discussion in itself. Forget that I even mentioned that part (it’s rather minuscule with most modern optics, but it does exist).
 
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nikonNUT

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The "cant" (technically cant is a horizontal aspect - angle or declination is the fancy technically accurate term) is to push the line of sight down into the bore line, so you gain the unused mechanical travel that would have been wasted. Not so much to optimize any optical qualities of any sort. For the scope, down is actually up - it gets confusing without really diving into the internal workings and such.

View attachment 7197793

If anything, the extra declination degrades optical quality - but that’s an entirely different discussion in itself. Forget that I even mentioned that part (it’s rather minuscule with most modern optics, but it does exist).
Declination, got it! I guess where I was coming from is that if I'm not planning on more that 1000 yards (8.1MRAD up) and I have 15 to work with is a 20MOA Spuhr with 30mm rings (All the scopes I've been looking at for a future build are 34mm) a necessity or am I over thinking it? Honestly, anything nearby is 550 max and 1000+ ranges are 6 to 7 hours away by car. 500 bucks buys a lot of ammo or a good mount for the next build! :) I really appreciate all the input and at the very least I am forarmed with the info I need for the future!
 
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AIAW

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Declination, got it! I guess where I was coming from is that if I'm not planning on more that 1000 yards (8.1MRAD up) and I have 15 to work with is a 20MOA Spuhr with 30mm rings (All the scopes I've been looking at for a future build are 34mm) a necessity or am I over thinking it? Honestly, anything nearby is 550 max and 1000+ ranges are 6 to 7 hours away by car. 500 bucks buys a lot of ammo or a good mount for the next build! :) I really appreciate all the input and at the very least I am forarmed with the info I need for the future!
If you can hit at the distance you are going for now there is no reason to change anything if you don’t want to. Remember also that you can always dial as much as possible and hold the rest in the reticle to make the shot.
 

Steel head

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Personally for cartridges like 308 or bigger/flatter I’d run a 20 at minimum.
30 being even better.
The majority of my shooting is 1000 to just over a mile.

if I was only shooting closer than that a 0 moa mount would certainly be an option.
 
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b6graham

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Give some consideration to the fact that rails are less than half the cost of mounts. In other words, if you're going to increase the angle of your scope, personally, I think it's best to buy a 20 MOA rail, as opposed to a 20 MOA mount. More flexibility/resale value for a 0 MOA mount.
not so easy on an AR platform..hence the spuhr 6mil mount
 
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seansmd

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If you can hit at the distance you are going for now there is no reason to change anything if you don’t want to. Remember also that you can always dial as much as possible and hold the rest in the reticle to make the shot.
This
 
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8pointer

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I have to ask, why a 200 yard zero? You are saving what, .3 MILs? Just complicates things in the long run.
While I don't use a 200 zero I stick with 100.....can you please expound on that last part as to complicating things? I've read that a few times, but am not smart enough to figure out the disadvantages. Thanks
 

b6graham

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While I don't use a 200 zero I stick with 100.....can you please expound on that last part as to complicating things? I've read that a few times, but am not smart enough to figure out the disadvantages. Thanks
200y zero adds variables.

when you have half a mil below zero and youre a .3, you lose that ability

not everything is an up elevation value anymore
 

AIAW

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While I don't use a 200 zero I stick with 100.....can you please expound on that last part as to complicating things? I've read that a few times, but am not smart enough to figure out the disadvantages. Thanks
A) Lack of environmental influence
B) PBR (mainly why hunters adopted further zeros) - Can still be dialed if desired
C) Overall easier to manage on some turrets
D) Doesn't save any real erector travel
 

8pointer

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A) Lack of environmental influence
B) PBR (mainly why hunters adopted further zeros) - Can still be dialed if desired
C) Overall easier to manage on some turrets
D) Doesn't save any real erector travel
Very good thanks. I was a B) buy MPBR so I could just raise up center lung and not hard to know if you are within MPBR with a 308. Makes perfect sense though.....zero at 100.....want MPBR just come up and leaveit.
 
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