Rifle Scopes S&B PM II question concerning MOA base.....

[Longbow_06]

Hi Guys.....

I understand that the M40's have a canted base for the S&B scopes. Can someone please explain how you work out how many MOA's you need in a base. And why do you need such a high MOA slope on the base for the S&B PM II.

Thanks.....

Lee.

 

[Goin'Hot]

Re: S&B PM II question concerning MOA base.....

To calculate the maximum base moa you can run:

Run your elevation knob all the way down and then run it all the way up. Count the total # of minutes you have and then divide it by 2.

For example, if you have 90 minutes of total elevation in your elevation turret, you could run a 40 moa base and you would still have 10 minutes of down which would allow you to zero at 100 yards.

On the up side, you would be able to dial 80 minutes up. This is usefull if you shoot a 308 and want to shoot long distances. You can never have too much "up elevation".

I say run as much moa in your base as possible and still retain a 100 yard zero. In this example, you could actually run a 45 moa base max which would allow you to retain all of your elevation for long shots.

 

[dieselten]

Re: S&B PM II question concerning MOA base.....

You don't NEED it. But if you want to be able to use every single fraction of the total elevation so you can shoot your rifle out to 3 or 4 miles, then yes, do all the math and figure out the exact base you need.

If you will not shoot past 1000 yards you probably do not need a canted base at all, as long as your rifle is not bent you can get by with a 0 MOA base.

Or you can do like 90% of all S&B owners do...buy a 20 MOA canted base and be done with it.

 

[Longbow_06]

Re: S&B PM II question concerning MOA base.....

So here's a dumb question.....

What happens when you have a 40 MOA base with a scope which only has 50 MOA internal travel.

Thanks in advance guys....

Lee.

 

[Rob01]

Re: S&B PM II question concerning MOA base.....

You will be zeroing at about 600 yards LOL Seriously a 40 MAO base is way too much for a scope with 50 MOA. Even a 20 MOA will be tough if you have to use any amount of windage when zeroing.

What scope are you looking at?

 

[Longbow_06]

Re: S&B PM II question concerning MOA base.....

LOL... Thats the answer I figured I'd get. I was using the Nikon Monarch X 2.5-10x44 with the 80 MOA of internal travel. I had forgotten that I had on a 40MOA nightforce base, which of course I could get away with this scope. I went and moved this scope to my AR predator rifle and ordered a Monarch X 4-16x50 for my .308.

Of course... This one only has 50 MOA internal travel. I realised what I'd done only yesterday. I just ordered a new Nightforce 20 MOA base.

Thanks for the replies.

Lee.

 

[One-Eyed Jack]

Re: S&B PM II question concerning MOA base.....

If (1) you're zeroing your centerfire rifle at 100 yards and (2) your scope has an equal amount of up and down elevation travel from optical center, then the maximum rail cant you can use is one-half the total elevation travel plus about 4 MOA.

Example: Your scope has 50 MOA of total elevation travel and you want to zero your rifle at 100 yards. Then the maximum rail cant you can use is (1/2 x 50 MOA) + 4 MOA = 29 MOA.

This does not work for 22LR because of its great bullet drop. For a 22LR, the maximum rail cant is one-half the total elevation travel plus about 14 MOA.