The Firing Line Forums

Go Back   The Firing Line Forums > The Skunkworks > Handloading, Reloading, and Bullet Casting

Reply
 
Thread Tools
Old May 9, 2008, 09:48 PM   #1
djonathang
Senior Member
 
Join Date: March 12, 2008
Posts: 165
Ballistics Tables and the real world?

Hello All,

Totally new to reloading, so this question will be as green as they come.

I took my first reloads to the range the other day. I'm shooting a .270 that is grouping nicely at 100 yards, 1 inch high.

My question is this: When I plug in my load data and look at the resulting ballistics tables for Hornady, it reads 0.0 at 100, 1.8" at 200, 4.3" at 300, etc. Since in the real world, I am up 1 at 100, can I simpy subtract 1" from each of the yardages listed, or is it more compicated than that? Unfortunatley, my range only has 100 yards as the max, so I can't get real life data for the other distances.

Thanks for the lesson.

DG
djonathang is offline  
Old May 9, 2008, 11:45 PM   #2
croc4
Senior Member
 
Join Date: March 9, 2006
Location: Santa Clara, Ca
Posts: 190
well.....

what is your scope/sights zero's for? I can take any load and place it any where on the target depending on how I adjust my sights, you need a base line load (but this does not really exist, your better off chasing windmills ;-) ), then adjust your sights to that then try your load. But all of that is not needed.
adjust your sights to where you want your load to place on the target at a given range and then guestimate as needed for what ever range beynd or before that, its pretty simple.

ballistic tables are nice, but are not scripture, just a god guide post
croc4 is offline  
Old May 10, 2008, 12:46 AM   #3
Bullet94
Senior Member
 
Join Date: September 8, 2004
Location: Kansas
Posts: 723
You might look here. You have to know the bullet weight and FPS. I find these are very close in the real world. You zero your load at 100 then adjust from there according to the data.

http://www.eskimo.com/~jbm/calculati...raj_basic.html


.
__________________
PRO-SECOND AMENDMENT - Live Free or Die
Bullet94 is offline  
Old May 10, 2008, 08:57 AM   #4
djonathang
Senior Member
 
Join Date: March 12, 2008
Posts: 165
Croc4,

Point well taken. My situation/question is this. I am now shooting 1" high at 100. I'd like to be 0 at 200, however my range only has a 100 yard range.

Within the confines of a 100 yard range, I want to prepare for a 200 yard shot.

The ballistics chart reads (for the same load/bullet) I will be 0 at 100. So, if I'm 1" high at 100, what should I expect at 200?

Bullet 94, I'll check out your link. Thanks.

DG
djonathang is offline  
Old May 10, 2008, 09:12 AM   #5
TimRB
Senior Member
 
Join Date: May 18, 2004
Posts: 1,028
"The ballistics chart reads (for the same load/bullet) I will be 0 at 100. So, if I'm 1" high at 100, what should I expect at 200?"

If I understand the info you've posted and what you've said so far correctly, then your understanding is correct-- your hits at 200 will be .8 inches low (in theory).

Tim

Edit: It probably would be more correct to adjust your program to show you 1inch high at 100 and see what happens at 200, but in practice there isn't a huge difference between 100 and 200 so YMMV.
TimRB is offline  
Old May 10, 2008, 09:24 AM   #6
djonathang
Senior Member
 
Join Date: March 12, 2008
Posts: 165
Thanks TimRB,

I really should have paid more attention in Geometry, or was it Physics

Cheers,

DG
djonathang is offline  
Old May 10, 2008, 09:25 AM   #7
Sarge
Senior Member
 
Join Date: May 12, 2002
Location: MO
Posts: 4,897
You'd need to know your 'sight height' and actual velocity, as well as the bullet profile, to draw any meaningful conclusions.

If you have those, then Ballistic Calculator can give a fair approximation of what to expect. Just remember that an approximation id\s all that it is, and you won't 'know' until you actually shoot at a given range.
__________________
Visit us at The Sixgun Journal or the archive, at http://sargesrollcall.blogspot.com/
Sarge is offline  
Old May 10, 2008, 10:04 AM   #8
rwilson452
Senior Member
 
Join Date: June 10, 2004
Location: Tioga co. PA
Posts: 2,359
to do what you want to do with any degree of accuracy your going to need to chronograph your load and apply the ballistic data to a ballistics program. your also going to need to do this on a calm day. otherwise your zero will be off by the wind. Remember your bullet doesn't follow a straight line but an arc. When you measure your sight height, if using a scope, you need to measure it from the center of the bore to the center of the scope. With iron sights measure from the center of the bore to the top of the front sight.
rwilson452 is offline  
Old May 10, 2008, 09:48 PM   #9
T. O'Heir
Senior Member
 
Join Date: February 13, 2002
Location: Canada
Posts: 3,142
What bullet weight?
__________________
Spelling and grammar count!
T. O'Heir is offline  
Old May 11, 2008, 12:16 AM   #10
djonathang
Senior Member
 
Join Date: March 12, 2008
Posts: 165
130 Grain
djonathang is offline  
Old May 11, 2008, 05:14 AM   #11
rwilson452
Senior Member
 
Join Date: June 10, 2004
Location: Tioga co. PA
Posts: 2,359
if you give me which bullet and how much of what powder your loading and give me sight hight I can give you a rough guess by assuming a velocity.
rwilson452 is offline  
Old May 11, 2008, 11:03 AM   #12
Sport45
Senior Member
 
Join Date: May 25, 1999
Location: Too close to Houston
Posts: 4,050
Quote:
Originally Posted by djonathang
can I simpy subtract 1" from each of the yardages listed, or is it more compicated than that?
It's a little more complicated than that but not a lot. As others have mentioned you need to have an accurate velocity and know the bullet properties and sight height. Then you set the ballistic calculator to zero at 200 yards. It will tell you the bullet should impact X high (or low) at 100 yards. Adjust your sights so that you are impacting at that measure at 100 yards and you should be close to zero at 200. Works better on scratch paper than on target paper, but will get you in the ballpark.
__________________
Proud member of the NRA and Texas State Rifle Association. Registered and active voter.
Sport45 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 07:25 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 0.09638 seconds with 9 queries