The Firing Line Forums

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

Reply
 
Thread Tools Search this Thread
Old July 31, 2020, 04:33 PM   #1
SFW
Senior Member
 
Join Date: June 23, 2010
Location: The Republic of Texas
Posts: 124
Reloading Data Discrepancies

So I'm working on a new load for my .308 AR. I am getting wildly different data on powder loads depending on what source I use. I will be using a Hornady 165 gain SST bullet. I plan to use Hodgdon Varget for the powder. From Hornady's reloading book I get 37.6 gr to 43.2gr. for available charge weights. From the Hodgdon website I get 42.0 to 46.0C. Not really sure which one to use at this point. Any insight would be great! Thanks!
SFW is offline  
Old July 31, 2020, 05:06 PM   #2
Unclenick
Staff
 
Join Date: March 4, 2005
Location: Ohio
Posts: 21,022
You want to use Hodgon's .308 Service Rifle data which is for gas guns. This has a maximum charge of 43.2 grains with a 168-grain match bullet, but that data will work for your 165.
__________________
Gunsite Orange Hat Family Member
CMP Certified GSM Master Instructor
NRA Certified Rifle Instructor
NRA Benefactor Member and Golden Eagle
Unclenick is offline  
Old August 1, 2020, 06:09 AM   #3
jetinteriorguy
Senior Member
 
Join Date: April 28, 2013
Posts: 3,152
Whenever I get large discrepancies I usually go with the lighter load, if it accurate within that range and no pressure signs I’m good. But if there is enough case capacity to go up within a higher recommended load and that’s what it takes to get better accuracy I’ll give it a go while watching for pressure signs. It’s all about being safe and starting low and working your way up.
jetinteriorguy is offline  
Old August 1, 2020, 07:04 AM   #4
hounddawg
Senior Member
 
Join Date: March 1, 2009
Posts: 4,232
when I see a large discrepancy I either go with the lightest as a starting load or look for a third source
__________________
“How do I get to the next level?” Well, you get to the next level by being the first one on the range and the last one to leave.” – Jerry Miculek
hounddawg is offline  
Old August 1, 2020, 07:29 AM   #5
RedSoxFan
Junior Member
 
Join Date: February 28, 2016
Posts: 6
Also,a chronograph is invaluable. While not 100% accurate, they'll give very useful feedback as to where you are within the load range.
RedSoxFan is offline  
Old August 1, 2020, 08:22 AM   #6
sparkyv
Senior Member
 
Join Date: May 2, 2015
Location: Deepinnaheartta,Texas
Posts: 318
This is sound advice:
Quote:
Originally Posted by jetinteriorguy View Post
Whenever I get large discrepancies I usually go with the lighter load, if it accurate within that range and no pressure signs I’m good. But if there is enough case capacity to go up within a higher recommended load and that’s what it takes to get better accuracy I’ll give it a go while watching for pressure signs. It’s all about being safe and starting low and working your way up.
__________________
μολὼν λαβέ
NRA Life Member
sparkyv is offline  
Old August 1, 2020, 08:28 AM   #7
Bart B.
Senior Member
 
Join Date: February 15, 2009
Posts: 8,927
Quote:
Originally Posted by RedSoxFan View Post
Also,a chronograph is invaluable. While not 100% accurate, they'll give very useful feedback as to where you are within the load range.
Note that a 308 Winchester will shoot the same load about 250 fps faster from a 30" barrel than a 20" one; both with the same bore and groove diameters.

Almost that much difference with same length barrels but a .002" difference in groove diameters.

Arsenals loading 7.62 NATO ammo see almost a 2 grain spread in charge weights across all bulk powder lots to meet velocity and pressure specs. Commercial 308 Winchester have less spread with canistered powder lots.

How tight bullets are gripped by case necks also effects average velocity and peak pressures. 7.62 M80 ball service ammo bullet pull force spec is 60 pounds minimum but M118 match ammo is 20 pounds minimum. No idea what commercial 308 Win ammo specs are. Never seen any bullet pull force spec in reloading data. SAAMI doesn't list any in their cartridge pressure and velocity standards. I've measured pull force on reloaded 308 ammo from 1 to 73 pounds.

Last edited by Bart B.; August 1, 2020 at 09:24 AM.
Bart B. is offline  
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search

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 06:55 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
This site and contents, including all posts, Copyright © 1998-2021 S.W.A.T. Magazine
Copyright Complaints: Please direct DMCA Takedown Notices to the registered agent: thefiringline.com
Page generated in 0.06279 seconds with 10 queries