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20 MOA base and interal adjustments

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Category: Scopes
Forum Name: Rifle Scopes
Forum Description: Centerfire long gun scopes
URL: http://www.opticstalk.com/forum_posts.asp?TID=40740
Printed Date: March/28/2024 at 17:08
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Topic: 20 MOA base and interal adjustments
Posted By: adillemu
Subject: 20 MOA base and interal adjustments
Date Posted: November/13/2014 at 10:39

I have a head scratcher here, hoping someone may be able to shed light on. I have a custom Rem 700 with a 6-24 Vortex Viper PST. The rifle shoots well (sub 1/2 MOA), scope tracks well and is very repeatable. The scope has and advertised 65 MOA of internal vertical adjustment. What I found this last weekend while shooting out to 1100 meters, was even with my 20 MOA base installed, I only have 30 MOA of vertical adjustment in the scope with a 100 yd zero. I's also add my windage adjustment & range of travel is as close to centered as I could expect it to be, within 2-3 MOA.


So essentially, my 20 MOA base put me back into the middle of my range of vertical adjustment in the scope, give or take a couple MOA. I understand all rifles and installations are a bit different. I was told by Vortex Tech Support that is why they make 20, 30 & 40 MOA bases. Is it just me or is this excessive?


Much thanks in advance.


Alan






Replies:
Posted By: SVT_Tactical
Date Posted: November/13/2014 at 11:48
In a perfect world when zero'ed at your ideal range you'd be dead in the middle of your scopes travel range in your case 65/2 = about 32.5 up and 32.5 down.   But more often than not its not the case. If you go to much of a cant on the base, 30 or 40 MOA you may not be able to zero at 100 because your bottomed out and no more adjustment.  Its a delicate balance when you have a scope with limited range.  You are not alone in your situation, happens to plenty of folks.

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Posted By: adillemu
Date Posted: November/13/2014 at 12:31

I got off the phone with an R & D guy at Vortex a few minutes ago. He shed some more light on the situation. He says this is quite common, they see it a lot. The rear pedestal on Remington 700 actions are hand finished during the manufacturing process. It's not uncommon to have significant material removed and variations from one rifle to the next. More material removed raises line of sight, drops point impact.

Looks like I will be bedding my base and re-lapping rings.

Thanks again for the input.



Posted By: cheaptrick
Date Posted: November/13/2014 at 12:39
Welcome to Optics Talk, Alan.  

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If at first you don't secede...try..try again.


Posted By: koshkin
Date Posted: November/13/2014 at 17:10
Many mass produced actions have significant variations in how the top of the receiver is finished.  I would not necessarily re-lap the rings right off hand.

You can add a shim between the base and the rear receiver ring and bed the whole thing.  Make sure you do not bend the base in the process.

ILya


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