20 moa Base question

[Squatch]

If I put a 20 or a 30 moa Base on a rifle, do normal ballistic calculators work or do I have to account for the scope no sitting level?

Thanks in advance for the info.

 

[Broz]

It will have no effect on the ballistic app. Once you zero at whatever distance, you will enter that info in the app and it will correct from there. Just check the amount of internal elevation your scope has and choose the base from there. For instance if you have 65 moa of internal adjustment in the scope, I would not go over a 30 moa rail to insure you can zero at 100 yards. Tell us what your scope has for internal elevation adjustment and we can recommend further.

Jeff

 

[Squatch]

I am putting a 6-24 pst with 65 moa adjustment on a 6.5x284.

 

[Broz]

I am putting a 6-24 pst with 65 moa adjustment on a 6.5x284.

Ok, in a perfect world and a good quality rail base, a 20 moa cant would give you 52.5 moa of elevation from a 100 yard zero. A 30 moa base would give you 62.5 moa. I think you would be able to get a 100 yard zero with both, but if the top of the receiver is off any, or the rail is off any, or the scope did not have a full 65 moa the 30 might be pushing it.

52.5 moa will get my 300 win mag to 1700 yards. Just short of a mile for reference.

Jeff

 

[Squatch]

Very cool. Thank you for the info. Sounds like the 20 moa Base is the way to go.

 

[Wisner74]

Ok, in a perfect world and a good quality rail base, a 20 moa cant would give you 52.5 moa of elevation from a 100 yard zero. A 30 moa base would give you 62.5 moa. I think you would be able to get a 100 yard zero with both, but if the top of the receiver is off any, or the rail is off any, or the scope did not have a full 65 moa the 30 might be pushing it.

52.5 moa will get my 300 win mag to 1700 yards. Just short of a mile for reference.

Jeff

How did you do that math on that? If you don't mind sharing.

 

[mikebob]

the way i figured mine after i zero rifle count how many moa or inches you can dial down the turret. .001 equals 1" at 100 yards

 

[Broz]

How did you do that math on that? If you don't mind sharing.

In a perfect world with all machining and specs perfect. a zero cant rail would give you give you 1/2 of the 65 moa the scope has up and the other 1/2 down. So 32.5 up or down. Then the 20 moa rail will move 20 moa from the down side to the up side equaling 52.5 moa up that you will now have for dial up. Then I ran the numbers in my Applied Ballistics app for my 300 win to find 52.5 moa was 1700 yards.

Jeff

 

[Wisner74]

In a perfect world with all machining and specs perfect. a zero cant rail would give you give you 1/2 of the 65 moa the scope has up and the other 1/2 down. So 32.5 up or down. Then the 20 moa rail will move 20 moa from the down side to the up side equaling 52.5 moa up that you will now have for dial up. Then I ran the numbers in my Applied Ballistics app for my 300 win to find 52.5 moa was 1700 yards.

Jeff

I like it, Thanks Jeff

 

[Squatch]

Does anyone have a recommendation on which base to buy for a cooper 52? Looking at a Talley.

 

[el matador]

In a perfect world with all machining and specs perfect. a zero cant rail would give you give you 1/2 of the 65 moa the scope has up and the other 1/2 down. So 32.5 up or down. Then the 20 moa rail will move 20 moa from the down side to the up side equaling 52.5 moa up that you will now have for dial up. Then I ran the numbers in my Applied Ballistics app for my 300 win to find 52.5 moa was 1700 yards.

Jeff

Great explanation. The only thing I see missing here is the few moa it takes to get zeroed. For a 200 yard zero it takes around 4 moa since your bullet starts out below your line of sight and drops a bit during the 200 yard flight. Of course the machining tolerances will vary, but I've yet to have a 20 moa rail give me more than 20 moa above center after zeroing. I've seen anywhere from 10-20, which makes sense if your tolerance is +/- 5 moa and you use 4 moa to get zeroed.

For a Cooper 52 the Talley is a good choice. Ken Farrel also makes one.

 

[Broz]

Great explanation. The only thing I see missing here is the few moa it takes to get zeroed. For a 200 yard zero it takes around 4 moa since your bullet starts out below your line of sight and drops a bit during the 200 yard flight. .

True and the reason I stated 100 yard zero. With the 100 yard zero the line of sight differences are more like 1.5 moa. This small difference will usually be less than the machining tolerances stacked up. Mostly in runs of actions and receiver top differences. Then you have the small issues like bore center and barrel centerline as well. That's why I stated "in a perfect world and also why I suggested the 20 would allow more room for error than shooting for the 30 when he only had 32.5 "in a perfect world" to borrow it from.

I myself have seen tolerances vary in less expensive rails. Like a 20 moa EGW I once purchased new that had 50 moa. Good thing I had a Nighrforce with 100 moa total elevation. Thus the reason in posts I stated " the use of quality rail"

Thanks
Jeff

 

[asg1485]

New here. Sorry for a stupid question. What you guys are saying is a 20 moa base for example takes away from the elevation in which the scope is capable of shooting? Am i completely off here?

Or do you gain elevation/distance?
So if u gain elevation you could potentially not have room to zero at 100?

 

[Squatch]

Yes, a 20 moa base essentially adds 20 moa worth of adjustment to you scope.
If I understand it correctly it will can't the scope down.