Long Range Hunting Online Magazine


Go Back   Long Range Hunting Online Magazine > Hunting > Long Range Hunting & Shooting

Long Range Hunting & Shooting Nightforce Optics


Reply

base ???

 
LinkBack Thread Tools Display Modes
  #1  
Old 02-13-2007, 09:11 AM
Bronze Member
 
Join Date: Feb 2007
Location: Arkansas Grand Prairie
Posts: 85
base ???

This is my first post, so here it goes. How far out will a 20moa base and a Leupold competition scope with 38min overall adjustment send a 165gr 300wm? Thanks for the knowledge guys, I've enjoyed this site so far.
Reply With Quote
  #2  
Old 02-13-2007, 09:50 AM
Platinum Member
 
Join Date: Oct 2005
Location: Michigan
Posts: 2,232
Re: base ???

There are a lot of unknowns here, but I'll give you some ideas.

Assuming a 24" barrel you'll get around 3200fps maximum for a 165gr Nosler Accubond. This bullet has a BC of .475

Your combination of 20MOA base and 38MOA adjustment range makes for a total of 58MOA vertical adjustment, BUT some of that is going to be used up in getting on a zero. Assuming that the scope would be about centered for a 100yd zero without the base (means that 19MOA is going to be used for a 100yd zero) giving you 39MOA vertical travel for 'reaching out there' (20MOA base + 1/2 of the scope travel).

For a 100yd zero, you will need around :
15MOA for 750yds,
25MOA for 1000yds,
39MOA for 1250yds.

Now I've made some pretty mighty assumptions that could be erring for or against you. For example, if the 165gr bullet you are using is a Hornady Spire point Interlock with a BC of only .387, you'll get almost to 1150 yds with 40MOA. If you have a 28" barrel, you can get to 3300fps, which lets you get to 1300yds with 39MOA.

But then again, maybe after you have sighted in, you have more than 39MOA left, or perhaps less?

Fill in a few of the details and we can help you a little more.

BTW: welcome to the forum.

Don
__________________
If some is good and more is better, then too much is just right.


My mind is a raging torrent, flooded with rivulets of thought, cascading into a waterfall of creative alternatives
Reply With Quote
  #3  
Old 02-13-2007, 10:16 AM
Gold Member
 
Join Date: May 2001
Posts: 920
Re: base ???

[ QUOTE ]
This is my first post, so here it goes. How far out will a 20moa base and a Leupold competition scope with 38min overall adjustment send a 165gr 300wm? Thanks for the knowledge guys, I've enjoyed this site so far.

[/ QUOTE ]

You will get between 1100 and 1200 yards.

Do keep the following in mind: because of the tolerances in actions, rails, and scopes, you may have a problem.

Ideally, a scope that has 38 MOA of total elevation, when set on an action... the central axis of the scope (19 MOA) will be parallel with the bore line. So if the boreline is pointing at the center of the target, the scope is pointing 1.5" above the center. So if you lower the cross hairs 1.5" you are now "Bore sighted". Now lower it one more inch for bullet drop, and you have 16.5 MOA left of elevation.

If you add a 20MOA base into the equation, you will get (in theory) 36.5 MOA of useful elevation. Your 100 zero should be 2.5" above the bottom of the elevation travel.

But... actions are not perfect, in fact they vary a lot in outer contour because they are hand finished on belt sanders. It will be possible that if the receiver bridge is high (by 5 or 6 thou) or the receiver ring is low by the same amount, you will not be able to zero the rifle at close ranges, and may have to settle for a close range zero of 300 yds.

Not theory - I have customers that had this problem.

Before buying a 20 base, mount the scope and zero the rifle at 100, and then count the MOA you have in the "DOWN" (moves the POI down).

You need 20 MOA or more, or you can't use a 20 MOA base.

If you don't have it, Leupold makes a 15 MOA base.

.
__________________
Here, kitty kitty kitty.

LRH member #23
Reply With Quote
  #4  
Old 02-13-2007, 01:14 PM
Bronze Member
 
Join Date: Feb 2007
Location: Arkansas Grand Prairie
Posts: 85
Re: base ???

Thanks guys,
Let me add some more info as I should have before. It's going on a 700 action. 26" barrel built by Bruce Broughton. I'm planning on using a tps base. 1000yd is as far as I plan on using it, I just wanted to verify my thoughts that a 20 cant base would sufice. If I went with more than 20moa would I still be able to zero it at 200yd?
Reply With Quote
  #5  
Old 02-13-2007, 02:23 PM
Gold Member
 
Join Date: Dec 2002
Location: mathias wv
Posts: 985
Re: base ???

ok, here's something else to think about, I had kirby build me a 7mm AM,on a rem 700, used a ken farrel 2 pc 20 moa base, IOR rings, and an XOTIC 4x16 USS, well I couldn't make zero at 100, not enough down in the scope, and this scope has 105 MOA of verticle adj. I replaced the farrel with a weaver GS 0 moa 2 pc base and got it zeroed it now has 87 MOA of "UP" left, only thing I can think of is an error in the reciever, base, or possibly the rings don't know which.
JS
__________________
Born to Hunt, Forced to Work!
Reply With Quote
  #6  
Old 02-13-2007, 04:39 PM
Bronze Member
 
Join Date: Feb 2007
Location: Arkansas Grand Prairie
Posts: 85
Re: base ???

That's why I think that the 20 should work. I'm pretty sure if I used any more that it wouldn't zero up close and any less it might not get out far enough. That's some of the draw backs of the scope I'm planning on using.
Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes


Similar Threads for: base ???
Thread Thread Starter Forum Replies Last Post
Ballistics question? 20 MOA base vs. 0 MOA base bowhunthard Rifles, Bullets, Barrels & Ballistics 7 08-07-2011 12:17 AM
Standard Base vs elevated base? kc Gunsmithing 6 10-19-2010 09:15 PM
Either EGW base or Remington base threads are way off, what to do? sdowney Gunsmithing 6 08-07-2009 11:03 AM
**SAVAGE BASE by FARRELL 30 Moa Base **REDUCED***** augustinaustin Optics For Sale 2 04-17-2008 04:53 PM
RDP 30MOA Base for LA M700--GREAT LR BASE Guns For Sale 0 12-04-2003 09:34 PM


All times are GMT -5. The time now is 12:57 PM.


Powered by vBulletin ©2000 - 2014, Jelsoft Enterprises Ltd.
Content Management Powered by vBadvanced CMPS
All content ©2010-2014 Long Range Hunting, LLC