The Firing Line Forums

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

Reply
 
Thread Tools
Old April 27, 2012, 06:58 AM   #1
rebs
Senior Member
 
Join Date: January 10, 2012
Posts: 2,196
group moved with a change in powder charge

I loaded 3 different loads for my S&W Sport with all using the same bullet, brand of case and primer. I used H335 powder with three different charges, 23.5 grs, 24.5 grs and 25.5 grs. The 23.5 didn't put one shot on the paper, the 24.5 posted a 1" group right on the right edge of the paper and the 25.5 was just off the right edge of the paper, so I didn't get a good look at the group as there was other peoples holes in the target holder.
Why did the group move to the right with a different powder charge ?
rebs is offline  
Old April 27, 2012, 07:04 AM   #2
Don P
Senior Member
 
Join Date: December 17, 2005
Location: Florida
Posts: 4,773
Perhaps its the shooter. Possibility is all I'm pointing out.
__________________
NRA Life Member, NRA Range Safety Officer, IDPA Safety Officer
As you are, I once was, As I am, You will be.
Don P is offline  
Old April 27, 2012, 08:36 AM   #3
SonOfGun
Member
 
Join Date: February 25, 2012
Location: Utah
Posts: 68
No 2 loads perform the same. Why would you assume they are going to have same POI? Each load has its own harmonics and will exit the barrel different. Keep trying different combinations untill you find what your rifle likes. If you fired THAT load in another rifle POI will change. It is a never ending quest for perfection.
SonOfGun is offline  
Old April 27, 2012, 09:24 AM   #4
Unclenick
Staff
 
Join Date: March 4, 2005
Location: Ohio
Posts: 10,195
It's normal to get some vertical stringing due to the different loads having a different bullet barrel times and exiting when the muzzle whip is in a different position. Having it happen horizontally, though, means the muzzle is moving horizontally, and that could be just due to the butt not being squarely in your shoulder so the gun moves with recoil. If you are left-handed, having shots move right as the butt slips left would be a possibility. Another possibility is some kind of uneven stock pressure on the barrel influencing muzzle position. You may have to float the front handguard to clear that. Any book on match accurizing AR's will show how that's done. I can't say I've seen it on a 16" barrel, personally, but I don't know why it couldn't be done.
__________________
Gunsite Orange Hat Family Member
CMP Certified GSM Master Instructor
NRA Certified Rifle Instructor
NRA Patron Member
Unclenick is offline  
Old April 27, 2012, 03:31 PM   #5
oneoldsap
Senior Member
 
Join Date: September 16, 2009
Location: I live in the foot of the Green Mountains of Vermont
Posts: 1,584
Different loads generate different barrel harmonics . Your POI could move in any direction , it's the size of the group that's important , the POI can be adjusted to point of aim !
oneoldsap is offline  
Old April 27, 2012, 04:34 PM   #6
Unclenick
Staff
 
Join Date: March 4, 2005
Location: Ohio
Posts: 10,195
I've had groups open up and shrink as well as moving vertically due to barrel time changes, and even go diagonal in gusting wind, but any horizontal stringing I've seen has always proved to be traceable to an addressable cause. Not counting shooter position issues, I've seen it where bolt lugs needed lapping because they were only making solid contact on one side, or where the inletting favored one side, and of course there's asymmetrical front stock contact with the barrel. A barrel that needed stress relieving will sometimes walk to the side as it heats, but that doesn't normally produce round groups. I still expect there will be something for him to identify that he can change.
__________________
Gunsite Orange Hat Family Member
CMP Certified GSM Master Instructor
NRA Certified Rifle Instructor
NRA Patron Member
Unclenick is offline  
Old April 27, 2012, 04:42 PM   #7
Strafer Gott
Senior Member
 
Join Date: May 12, 2011
Location: New Mexico
Posts: 1,118
What's the target range? I've been using comparable loads of H335 with a NATO barreled Colt Sporter, 24.5grs to be precise, with good results.
Load like that and adjust your sights. You probably are experiencing a little barrel whip. That 1" group is pretty good, and adjusting sights is easier than chasing a load. I've tried other powders, but come right back to H335.
Are you using a sling?
Strafer Gott is offline  
Old April 27, 2012, 06:28 PM   #8
amamnn
Senior Member
 
Join Date: May 13, 2006
Location: WA, the left armpit of the USA
Posts: 1,323
as mentioned--what range? wind direction and velocity? Sounds like some sights/scope zeroing was reqired? how many shots in a "group?" what kind of rest was used? was the bench stable? was the shooter stable? were there horses in the stable? Was there a dog in the manger? Inquiring minds want to know...........
__________________
"If the enemy is in range, so are you." - Infantry Journal
amamnn 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 12:11 PM.


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 0.07211 seconds with 9 queries