How many MOA do I need to reach out to 1000 yards?

[colbyshoots]

I'm looking to order up a base for my Ruger American and can't decide which size base (20 or 30 MOA) to get. Any help would be much appreciated!

If it matters, my scope will have 31 MRAD of elevation adjustment.

[tdbru]

That depends a lot on the bullet you're using and the muzzle velocity you are achieving.

if you go to some of the web ballistic calculators and fill in the data, they can help a lot. for example : https://www.hornady.com/team-hornady...ic-calculators

-tdbru

[Klem]

Colby,

With a high BC bullet in the Grendel velocity range you're going to need up to 15 Mils of elevation to get to 1K yds.

Your scope will be roughly half up and down, so at 0 cant you already have 15.5 Mils of available elevation. Add to that another 6 Mils for a 20MOA base (3.438 MOA = 1 Mil) and you have 21 Mils of dial-up elevation. A 20MOA base is more than enough.

[colbyshoots]

That depends a lot on the bullet you're using and the muzzle velocity you are achieving.

if you go to some of the web ballistic calculators and fill in the data, they can help a lot. for example : https://www.hornady.com/team-hornady...ic-calculators

-tdbru

I'm not well versed in those calculators but I'll give it a whirl.

[colbyshoots]

Colby,

With a high BC bullet in the Grendel velocity range you're going to need up to 15 Mils of elevation to get to 1K yds.

Your scope will be roughly half up and down, so at 0 cant you already have 15.5 Mils of available elevation. Add to that another 6 Mils for a 20MOA base (3.438 MOA = 1 Mil) and you have 21 Mils of dial-up elevation. A 20MOA base is more than enough.

Thanks Klem. Do you think there would be any reason to step up to a 30 MOA base? Is there any PRO to using a 30 MOA vs a 20 MOA?

[Klem]

Thanks Klem. Do you think there would be any reason to step up to a 30 MOA base? Is there any PRO to using a 30 MOA vs a 20 MOA?

Not in this calibre. Grendel is slower than a wet week thanks to its small case and so is not suited for long range shooting. Your bullet will get there but will be wobbling around the sky after 800yds as it crosses into transonic (1,350fps). As it slows the bullet's centre of gravity moves forward and in a pointy supersonic shaped bullet that means it starts to go unstable. Groups blow out, and by 1K it is subsonic.

With 20MOA cant you have enough to make 1K easily but with 30MOA it is useless elevation because the calibre is going to let you down if you want to use the extra elevation 15.5 (scope) + 9 (base) = 24.5Mil max elevation = roughly 1,400yds/900fps. Trying to be accurate at that range will be like driving jelly.

[VASCAR2]

[colbyshoots]

Not in this calibre. Grendel is slower than a wet week thanks to its small case and so is not suited for long range shooting. Your bullet will get there but will be wobbling around the sky after 800yds as it crosses into transonic (1,350fps). As it slows the bullet's centre of gravity moves forward and in a pointy supersonic shaped bullet that means it starts to go unstable. Groups blow out, and by 1K it is subsonic.

With 20MOA cant you have enough to make 1K easily but with 30MOA it is useless elevation because the calibre is going to let you down if you want to use the extra elevation 15.5 (scope) + 9 (base) = 24.5Mil max elevation = roughly 1,400yds/900fps. Trying to be accurate at that range will be like driving jelly.

LOL, driving jelly. I've never heard of that but that pretty much sums it up. Sounds like a 20MOA base will be plenty for what I'll be doing.

[VASCAR2]

Here is a link to the Diversified Products 25 MOA mount I use on my Cz527. They have canted mounts for other brands of rifles.

https://www.diproductsinc.com/Detail.aspx?PROD=1189982&CAT=4268

[colbyshoots]

I had to look it up as mine is in MRAD but this scope has 110 MOA of adjustment!

I'm in southern WI so I think we are pretty close in elevation.

[lazyengineer]

Not in this calibre. Grendel is slower than a wet week thanks to its small case and so is not suited for long range shooting. Your bullet will get there but will be wobbling around the sky after 800yds as it crosses into transonic (1,350fps). As it slows the bullet's centre of gravity moves forward and in a pointy supersonic shaped bullet that means it starts to go unstable. Groups blow out, and by 1K it is subsonic.

With 20MOA cant you have enough to make 1K easily but with 30MOA it is useless elevation because the calibre is going to let you down if you want to use the extra elevation 15.5 (scope) + 9 (base) = 24.5Mil max elevation = roughly 1,400yds/900fps. Trying to be accurate at that range will be like driving jelly.

This is a great reply.

I tried running mine at 1000. It didn't work because E-targets needed it to be good supersonic still to work.

I tried it at 1000 on a gong range. It did work pretty decent, but I definately needed a friend on strong glass to see and call the impacts. It's quite mild at that distance, so not a lot of noise or plate movement on impact.

Grendel is a damned fine round, and can make it to 1000 yards, but where it shines and dominates is more on an NRA or CMP 600 yard midrange match. (IMHO)

[lazyengineer]

To the OP, I found 20 MOA offset to just barely leave enough room to still fit a 100 yard zero. 30 MOA and in my case I wouldn't have.

[colbyshoots]

To the OP, I found 20 MOA offset to just barely leave enough room to still fit a 100 yard zero. 30 MOA and in my case I wouldn't have.

Thank you for that. I was wondering how close the 30 MOA would be.

[lazyengineer]

Thank you for that. I was wondering how close the 30 MOA would be.

YMMV of course, but 6.5 Grendel just isn't the round for a 30 MOA offset, IMHO.

I Just wish someone made a cost effective offset mount

[tdbru]

Klem,
did you mean to say that the center of pressure moves forward, rather than the center of gravity? I would think the center of gravity for an object like a bullet that is a solid shape remains the same. It's my understanding, perhaps wrong, that the further forward of the CG the CP is, the faster you have to spin the bullet to keep the pointy end headed down range first. i.e. short bullets take less spin than long bullets. My understanding is that the spin will still keep the bullet going pointy end first, but as you transition the sound barrier the CP does move which causes a random dispersion to the trajectory which is why the groups open up as the bullet goes from supersonic to subsonic.
please clarify if I have it wrong.
thanks,
-tdbru