What M.O.A base do I need?

[Williamb]

I read with interest the thread on what base and rings will I need but I still have some questions.

I am currently putting together a 6mmBR on a Savage target action with target contour barrel. This will principally be used for paper punching and varminting. My short zero will be at 100 yards but I am also interested in ensuring that I can use the rifle up to a 1000 yards even though I am anticipating most of my use will be at 600 yards or less. I am expecting to put on either a Nightforce Benchrest,40 M.O.A vertical adjustment) or NXS 12 – 42x,45 M.O.A) scope with Ken Ferrell Steel Bases and rings. My question is what MOA base will be optimal for my needs?

I am unsure if I should use 10 M.O.A or use 20 M.O.A bases? Wondering if there is an optimal place to be at within your elevation range when at a 100 yard zero and I am assuming the 10 or 20 MOA bases will effect actual versus optimal elevation adjustment at 100 yards. However if 10 MOA bases give me optimal elevation location but I can't reach a 1000 yard adjustment then I will need to go to a 20 base.

I am sure I am agonizing over this too much but my gut feel is 20 MOA bases – your suggestions are appreciated.

Thanks -

 

[billmo]

I think you would be perfectly happy with 20 MOA. I have three rifles with Ferrell 20 MOA bases mounted on them and they work fine.

 

[Williamb]

billmo -

Thanks for the quick response. What are the advantages or disadvantages of aluminum versus steel bases/rings? I prefer steel but I received a suggestion to use aluminum.

Thanks

 

[FALPhil]

Ferrell's stuff is excellent, and you cannot go wrong with either one. Aluminum gives you a weight saving, and that is the only thing I can think of which would be an advantage of one over the other.

 

[billmo]

billmo -

Thanks for the quick response. What are the advantages or disadvantages of aluminum versus steel bases/rings? I prefer steel but I received a suggestion to use aluminum.

Thanks

Man, I think it is a matter of preference. I like Ken Ferrell's bases because of cosmetics as much so as any other aspect. As far as rings go Phil covered that well. The only other thing I would acknowledge is if you need to lap your rings in order for your scope to mount square in the rings, the aluminum will lap in easier of course. Otherwise, one and the same to me.

 

[skinewmexico]

I had a 20 MOA Farrell base on a Savage 6.5X47 Lapua, and ran out of down adjustment using a Bushnell 4200. I will admit that the 4200 is kind of known for not having much elevation adjustment. Same thing happened when I had that setup on a 223. It was zeroed @ 300 with the scope bottomed out. So I guess I'm saying I would go with a 10. If you were lobbing 308s, it might be different. Run some numbers on the JBM ballistics calculator, and you'll know for sure. Or use Burris Signature Zee rings, and you can always change the inserts to offset inserts to get additional MOA if you need it. While not marking up your scope.

If any scope has the adjustment to make a 20 work, the Nightforce is it.

 

[Williamb]

gunamonth -

Thanks for the thorough explanation. After following your logic I opened up my ballistics calculator and ran some B.C.s / velocities/ distances and totally agree with you. I need 15 M.O.A. bases.

Thanks -

 

[icepick]

Thats odd.
I'm using the NXS 42 X with a NF 20min. one piece base.
If i adjust the scope all the way down till it stops I'm bang on a 200 yds. I have to hold low at 100.

When I go out to 1000 I think the last setting was about 27 min.
I'm shooting a 107 smk around 2900.

M.

 

[Williamb]

Icepick -

I think the difference is that I wanted my close zero to be 100 yards without needing to hold low. With 15 M.O.A. bases I will have enough vertical come-ups with the Nightforce 12-42.

Thanks -

 

[alf]

You can crunch all the numbers you want, but it's highly unlikely, once you mount the scope, that it's gonna be dead center in the middle of it's adjustment range.

I'd probably lean towards the 20 moa base.

Al

 

[Williamb]

Al -

If you read gunamonth's explanation it is not to have the scope centered in the middle of the adjustment range it is to have enough vertical adjustment to accomodate a 100 yard zero along with vertical adjustment M.O.A.s for 1000 yards. This is what I was initially asking about.

Thanks -

 

[alf]

William,

If you re-read Gunamonth's first paragraph, he's assuming the scope will be mounted in the middle of the scope's adjustment range, then, of course his caculations are valid. The 12x42 BR's do only have 40 moa total movement.

You still won't have a clue where YOUR scope will be pointed until it actually mount it.

Al