Rifle Scopes Rail cant question for a 338

[mrtoyz]

Please check my logic...

338LM
300gr
2700fps
1760yds

Vortex PST ffp 24x, Max Elevation Adjustment 19 mrads

My handy dandy Ballistic FTE app shows 21.71mrad drop at 1760yds.

1moa=3.438mrad

20moa rail would add 5.81mrad adj(20/3.438=5.81) Total elevation adj would be 24.81mrad using the Vortex.

Correct or incorrect?

Also wondering how I can calculate the minimum distance any give rail would allow?

Yes I know 1760yds...a guy can dream...

Appreciate your time.

-T

 

[Trigger Monkey]

Re: Rail cant question for a 338

No, you're making some incorrect assumptions. 19 mrad isn't the amount of elevation you'll have available it's the total amount of elevation within the tube. Generally scopes come to the customer centered to allow for zeroing on different weapons so that means it'll more than likely have 9.5 mrad above and below center. If you use a 20 MOA base the best you can probably hope for is 15 mils or so of elevation travel. Unfortunately going to 30 MOA base will only yield about 18 mils of elevation travel and you'll only be about a mil or so from bottoming out. Going by the numbers I'm just not sure if you'll be able to reach the mythical mile with this particular set up.

 

[mrtoyz]

Re: Rail cant question for a 338

I thought about that. I was thinking that max elevation adjustment was referring to up elevation. You see total elevation, max elevation and I was never total sure exactly the difference.
Bummer.
No wonder NF's come with 100moa of "total" adjustment.
So to hit my mythical mile mark I'd need a 40moa rail to use the Vortex, but then how does that affect my minimum distance?

Thanks.

-T

 

[TimResin]

Re: Rail cant question for a 338

you would be stuck with a 425 yd zero which isn't a big deal considering your shooting a .338

 

[ChrisGarrett]

Re: Rail cant question for a 338

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: mrtoyz</div><div class="ubbcode-body">I thought about that. I was thinking that max elevation adjustment was referring to up elevation. You see total elevation, max elevation and I was never total sure exactly the difference.
Bummer.
No wonder NF's come with 100moa of "total" adjustment.
So to hit my mythical mile mark I'd need a 40moa rail to use the Vortex, but then how does that affect my minimum distance?

Thanks.

-T </div></div>

Don't forget, that Murphy's Law comes into play, more often than not, in this circumstance.

You have 19 mils total travel, but did you confirm this with windange centered?

You might really have 20.4, or 18.7.

Secondly, assuming 19 is the total travel you have upon confirmation, you're taking a leap of faith if, after getting everything mounted, you think that you're going to be dead center at 9.5 mils of UP left.

Hommie don't think so. Things are never that elegant.

Chris

 

[mrtoyz]

Re: Rail cant question for a 338

Tim can you eplain how you calculate 425yds?

-T

 

[mrtoyz]

Re: Rail cant question for a 338

AH! I've got it.
Same senario with corrected elevation numbers (correctly divided up and down) and 100 yd zero.

19mils of total travel in scope. 9.5 up and 9.5 down (assuming zero is at center)

Add a 40 moa base (11.63mils) I would htne have 21.13mils up and "-2.13 mils" down. (Need 21.71 mils to reach 1760yds) In other words I would be mechanically bottoming out trying to return to a 100yd zero.

The Ballistic clac shows that 2.13mils is approximately 425yds....

I could use mils on the reticle....looks like I'd pic up 8mils up and 8 mils down...

SO in theory....using the reticle I "could" get from 100yds to 1760yds?? LOL

AH HA?!?