The Firing Line Forums

Go Back   The Firing Line Forums > The Hide > The Art of the Rifle: General

Reply
 
Thread Tools
Old January 13, 2011, 04:01 PM   #1
jeepman4804
Senior Member
 
Join Date: February 13, 2008
Posts: 211
.308 win and 7.62x51 trajectory w/ 50 yard sightin

Looking for some guidance on this matter. I want to use a 50 yard sight-in on my newest .308 ar but would like to know what I can expect trajectory wise until I can confirm in via paper. I plink with surplus 7.62x51 and will be shooting 168grain .308 for killin stuff.

With a 50 yard sight-in and standard height iron sights what would my poa/poi be a 25 yards (all I have till Saturday)?

I know some of you are genius with this stuff so any insight will help.
jeepman4804 is online now  
Old January 13, 2011, 04:12 PM   #2
jman841
Senior Member
 
Join Date: March 18, 2009
Posts: 575
http://www.winchester.com/learning-c...alculator.aspx

should be able to help you
jman841 is offline  
Old January 13, 2011, 04:21 PM   #3
Rimfire5
Senior Member
 
Join Date: January 2, 2009
Location: Northern Virginia
Posts: 496
With a 168 grain bullet and 2650 fps muzzle velocity (Federal Match with Sierra Match Kings) and your scope center 1.5 inches above the barrel center, sighting in your zero at 50 yards would mean that the round would be
0.59 inches low at 25 yards,
0.14 inches high at 100 yards
1.27 inches low at 150 yards
4.44 inches low at 200 yards.

You didn't say what weight the plinking ammo was or what the muzzle velocity was.

If the plinkers were 147 grains at 2550 fps, and a 50 yard zero, the plinking ammo would be
0.57 low at 25 yards
0.04 high at 100 yards
1.65 low at 150 yards
5.12 low at 200 yards.

I hope that helps.
Rimfire5 is offline  
Old January 13, 2011, 05:00 PM   #4
jeepman4804
Senior Member
 
Join Date: February 13, 2008
Posts: 211
Plinkers are the 147 gr variety. And that helps a bunch! Thanks.

1 more quick question. The barrel I have is 1 in 10 twist... Think I should experiment with a little heavier projectile?
jeepman4804 is online now  
Old January 13, 2011, 05:10 PM   #5
PawPaw
Senior Member
 
Join Date: December 24, 2010
Location: Central Louisiana
Posts: 3,115
Interesting question. The old timers would tell you that a 25 yard zero will put you close enough in the ball park to kill game out past 200 yards.

So, I got out my ballistics calculator and found the folllowing interesting fact about my .30-06 hunting load.

2900 fps, .30-06, 150 grain Nosler Ballistic Tip

25 yards. - 0.00
50 yards - +1.20
100 yards - +2.78
150 yards - +3.16
200 yards - +2.24
250 yards - 0.00
300 yards - -3.80 inches.

That's very interesting, and is purely theoretical, but I've found that this program closely approximates what I see in the field.

Quote:
1 more quick question. The barrel I have is 1 in 10 twist... Think I should experiment with a little heavier projectile?
Naah, 1:10 is standard for .30 caliber in this country. It'll shoot those weights just fine.
__________________
Dennis Dezendorf

http://pawpawshouse.blogspot.com
PawPaw is offline  
Old January 13, 2011, 05:21 PM   #6
jeepman4804
Senior Member
 
Join Date: February 13, 2008
Posts: 211
so a 25 yard zero would probably suit me a little better for a do all gun by the looks of it.
jeepman4804 is online now  
Old January 13, 2011, 05:49 PM   #7
jeepman4804
Senior Member
 
Join Date: February 13, 2008
Posts: 211
.308 Win. Hornady TAP FPD 168 Grain 2700 fps is what I will be using on a regular basis. If that helps any. I am very new to the .308 world.

I have a .556 for work and my deer guns are .243, .270, and my 30-06 gets the most use. I am just now getting into the longer range interests as 150yards and under is just plain boring now.
jeepman4804 is online now  
Old January 13, 2011, 06:03 PM   #8
PawPaw
Senior Member
 
Join Date: December 24, 2010
Location: Central Louisiana
Posts: 3,115
Quote:
I am just now getting into the longer range interests as 150yards and under is just plain boring now.
If you get out past 150 yards, none of this might be any good. This is all theoretical and there's nothing like actually testing your skill at the ranges you'd like to use them. A 50 yard zero should put you on paper, but for longer work, a good sight-in is critical. The ballistics tables would help, but there's nothing like actually shooting at those ranges.

Unless I'm sadly mistaken, the military is now using 175 grain Matchkings for long-range work in the 7.62 round. They find it carries better at long ranges.
__________________
Dennis Dezendorf

http://pawpawshouse.blogspot.com
PawPaw is offline  
Reply

Thread Tools

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 -5. The time now is 10:38 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
This site and contents, including all posts, Copyright © 1998-2014 S.W.A.T. Magazine
Copyright Complaints: Please direct DMCA Takedown Notices to the registered agent: thefiringline.com
Contact Us
Page generated in 0.08140 seconds with 7 queries