Long Range Hunting Online Magazine


Go Back   Long Range Hunting Online Magazine > Rifles, Reloading, Optics, Equipment > Reloading

Reloading Techniques For Reloading


Reply

Pet load showing sudden pressure?!

 
LinkBack Thread Tools Display Modes
  #1  
Old 09-07-2010, 09:12 AM
Bronze Member
 
Join Date: Oct 2007
Posts: 65
Pet load showing sudden pressure?!

Need your help. Been doing some ladder testing with my 7 mm RM and found a load that had a low vertical dispersion at 1,000 yards. The load showed no pressure signs and was developed in temps above 90. I shot the same load yesterday in 70 degree weather and my brass, primer, bolt showed major pressure signs. I've changed nothing... Here is some basic information:

Load is 72.5 gr of Retumbo (I know it's hot but was working before)
168 grain bergers
Fed 215 GM primers
Brass is on 4th shooting
I've only bumped shoulders and bushing sized the necks (which are turned)
I've only shot about 200 rounds through the barrel with proper break-in
I clean thoroughly after 20 plus rounds

Why did this load work before and now seems way too hot? The speed jumped so much I was over my target a couple of feet. I'm fairly meticulous with my load development so I am sure I didn't change anything from before.

Does anyone know what would cause this to happen?
Reply With Quote
  #2  
Old 09-07-2010, 09:17 AM
Platinum Member
 
Join Date: Feb 2007
Location: Townsend, Montana.
Posts: 7,937
Re: Pet load showing sudden pressure?!

ammo laying in the sun?

Chamber hot form firing a string of rounds?

This is pretty much why I quit using Retumbo in one of my 30-378's. I was close to max and knew it, but the next time out it stuck the bolt. I changed to H-1000 and have been happy since.

Jeff
__________________
Reply With Quote
  #3  
Old 09-07-2010, 09:22 AM
Platinum Member
 
Join Date: Nov 2005
Location: Texas
Posts: 1,844
Re: Pet load showing sudden pressure?!

As stated above-----something has changed. This is a common issue when shooting marginal loads. Be smart when working up your loads.
__________________
The Truth Is Not Always Good For Business!!
Reply With Quote
  #4  
Old 09-07-2010, 09:34 AM
Bronze Member
 
Join Date: Oct 2007
Posts: 65
Re: Pet load showing sudden pressure?!

We were shooting out of the shade (the brass was cold) and my second shot out of the barrel showed bad ejector marks and the bolt was very difficult to lift.

Obviously I'm backing off of 72.5 by at least a grain but was just curious as to what could have caused this sudden jump in pressure. Maybe the best explanation is that it was a "marginal," inconsistent load...
Reply With Quote
  #5  
Old 09-07-2010, 06:40 PM
Silver Member
 
Join Date: Jan 2007
Location: Ohio
Posts: 163
Re: Pet load showing sudden pressure?!

I ran into this problem with a .22-6mm when I had the barrel set back and rechambered. I figured it was due to the shortening of the throught. Primer changes can have an effect also. A different lot of powder can also change things. Brass with a slightly smaller capascity will cause it. I`m sure I`m missing some, but this is a strat of where to look.
Reply With Quote
  #6  
Old 09-08-2010, 12:58 AM
Bronze Member
 
Join Date: Oct 2007
Posts: 65
Re: Pet load showing sudden pressure?!

I'm using a redding body die to bump the shoulder back. That may have tightened it up a bit? And come to think of it I did just buy another can of Retumbo which was used for these loads. It went from zero pressure signs at 72.5 grains to major pressure with the same load. It scares me that a different lot of powder could produce such drastic changes in pressure.

I hadn't thought of that possibility.
Reply With Quote
  #7  
Old 09-08-2010, 01:07 AM
Platinum Member
 
Join Date: Oct 2009
Location: Thunder Basin, WY
Posts: 1,788
Re: Pet load showing sudden pressure?!

They used to say "when you find a good lot of powder or primers that work for you, buy 8 lbs of that lot and alot of primers" I know this isn't always possible to do, sometimes its impossible if that particular stuff is really popular, but I guess this is one of those situations when it would apply?

Last edited by SBruce; 09-08-2010 at 09:02 AM.
Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes


Similar Threads for: Pet load showing sudden pressure?!
Thread Thread Starter Forum Replies Last Post
.243 fusion Factory showing high pressure fmsniper Rifles, Bullets, Barrels & Ballistics 2 06-19-2011 12:48 PM
.260 load pressure problem Gota6.5 Reloading 7 02-09-2011 06:09 PM
.204 Load/ Pressure signs? ovastafford Reloading 3 04-17-2010 05:09 PM
Showing signs of excess pressure/what next? goose Reloading 7 12-28-2008 09:19 AM
brass showing pressure signs at lower powder charges with subseqent firings jmden Rifles, Bullets, Barrels & Ballistics 3 05-02-2004 02:50 PM


All times are GMT -5. The time now is 04:30 AM.


Powered by vBulletin ©2000 - 2014, Jelsoft Enterprises Ltd.
Content Management Powered by vBadvanced CMPS
All content ©2010-2014 Long Range Hunting, LLC