Calguns.net  

Home My iTrader Join the NRA Donate to CGSSA Sponsors CGN Google Search
CA Semiauto Ban(AW)ID Flowchart CA Handgun Ban ID Flowchart CA Shotgun Ban ID Flowchart
Go Back   Calguns.net > CALIFORNIA SHOOTING CLUBS AND ORGANIZATIONS > California Precision Rifle Club
Register FAQ Members List Calendar Mark Forums Read

California Precision Rifle Club California Precision Rifle Club Forum

 
 
Thread Tools Display Modes
Prev Previous Post   Next Post Next
  #1  
Old 01-27-2010, 10:47 AM
ar15barrels's Avatar
ar15barrels ar15barrels is offline
I need a LIFE!!
 
Join Date: Jan 2006
Location: Van Nuys
Posts: 38,688
iTrader: 88 / 100%
Default How to use your scope

I'm working on a new thread and would like comments before I finalize it and have it stickied.

About bullet drop.
We know that the bullet drops as it travels down range.
Ballistic calculators will tell you how much the bullet drops if you give them all the proper data to calculate it.
Our scope's line-of-sight is above the barrel by an inch or two.
Gravity starts acting on the bullet as soon as it leaves the barrel.
Therefore, we have to point the barrel up in order to reach our 100yd zero.
This is to account for both the bore to scope height as well as bullet's drop from the line of departure.
This will cause the bullet to cross the line-of-sight around 85-90yds on a typical 308 load and then drop back down to your exact aiming position at 100yds.

When you are turning the scope knob, you are moving the reticle around within the scope.
Since we use the reticle to POINT the gun, what we are really doing is changing where the barrel is pointing.
So, we are using the scope's knobs to change the ANGLE of the barrel in relation to the line-of-sight.
This is really important to grasp because everything references back to the angle that you launch the bullet.

In order to hit targets that are farther away, you have to point the barrel up some more.
The graphic below calls the barrel angle the "line of departure".



With a 200yd zero, the bullet is probably crossing the line-of-sight around 50yds.

Last edited by ar15barrels; 04-06-2010 at 10:05 PM..
Reply With Quote
 

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump



All times are GMT -8. The time now is 7:22 PM.




Powered by vBulletin® Version 3.8.9
Copyright ©2000 - 2016, vBulletin Solutions, Inc.
Proudly hosted by GeoVario the Premier 2A host.
Calguns.net, the 'Calguns' name and all associated variants and logos are ® Trademark and © Copyright 2002-2016, Calguns.net an Incorporated Company All Rights Reserved.