Long Range Hunting Online Magazine


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

Reloading Techniques For Reloading


Reply

Severely Dented Cases….Secondary Explosion Effect?

 
LinkBack Thread Tools Display Modes
  #1  
Old 09-17-2013, 08:43 AM
Junior Member
 
Join Date: Dec 2012
Posts: 14
Severely Dented Cases….Secondary Explosion Effect?

Any help, advice, or ideas would be greatly appreciated... So here's the details, I'm shooting a 7mm ultra mag. Two days ago, I shot a 0.5" group with 88 gr RL-25 in once fired brass, federal 215M primer, and 140 gr nolser accubond. Once back at home, I loaded another 5 rounds with the identical load but the only differences were that I used new Remington brass and had to open a new sleeve of primers. The following morning, I headed back to the range. It resulted in big dents being left right in front of the case shoulder. There was burned powder on the outside of the case like gas entered between the chamber and the case.
What I have read on this subject and the secondary explosion effect leans towards the idea that: 1.) the load is too light, 2.) the powder is burning to slow causing the case not to expand completely to the chamber wall. I then shot even a lighter load (87 gr) in a once fired case and everything was fine. Also re-tested it with the same load from the day before......
Long story short, the big dented cases were replicated 3 times, all with new brass and primers from a different sleeve. Anytime once fired brass was used, everything worked great. I am going to try a load with the new brass and some retumbo powder to see if the slightly faster burn rate will help….

I have shot this particular load (88gr RL-25) in multiple ultra mags prior to this one and they all shot amazing.

Could it be a bad batch of brass?
Or the new brass possibly stiffer, and therefore not expanding enough?
The primers are slightly defected causing the powder not to burn fast enough?

Any help would be great. Thanks everyone
Attached Thumbnails - Click to View Larger
Severely Dented  Cases….Secondary Explosion Effect?-rifle1.jpg   Severely Dented  Cases….Secondary Explosion Effect?-rifle2.jpg  

Reply With Quote
  #2  
Old 09-17-2013, 09:19 AM
Silver Member
 
Join Date: Mar 2012
Location: New germany, NS
Posts: 286
Re: Severely Dented Cases….Secondary Explosion Effect?

GOOD question!
I have never seen anything that severe. The only thing that comes close in my memory was many years ago I was at a NSRA range where they where handing out 7.62 nato (military issue stuff), during a gentlemans competition. We where of course using bolt actions in 308win. In almost all of the brass shot there that day the same dents where there BUT, although the dents were there in almost the same place they were very small.
So it may just be the brass, reload it and see if it does not correct itself
Reply With Quote
  #3  
Old 09-17-2013, 09:24 AM
Junior Member
 
Join Date: Dec 2012
Posts: 14
Re: Severely Dented Cases….Secondary Explosion Effect?

Thanks for the input. I am leaning towards the idea the the powder charge is not burning hot and quick enough to fully expand the new case. I am going to try 92+ grains of retumbo tonight and see if that will work. It makes me a little nervous to shoot the rifle with light loads now, but i am not knowledgable enough on the subject to determine how dangerous this is...Thanks again
Reply With Quote
  #4  
Old 09-17-2013, 09:48 AM
dig dig is offline
Gold Member
 
Join Date: Sep 2010
Location: Arizona
Posts: 564
Re: Severely Dented Cases….Secondary Explosion Effect?

You may try cleaning the chamber real well. I know you said only one load causes tjis but something is not sealing.
__________________
Digger
Reply With Quote
  #5  
Old 09-17-2013, 01:24 PM
Bronze Member
 
Join Date: Apr 2013
Location: Tucson Arizona
Posts: 38
Re: Severely Dented Cases….Secondary Explosion Effect?

Have seen this once before years ago (1985). Pre '64 264 Winchester Magnum with 140 grain Nosler solid base bullets, cci 250 primers and IMR 4350.

The only remedy we found at the time was to switch to a slower burn rate powder, back in 1985 options were limited. We found that H870 was the only powder that fixed the collapsed shoulders. It shot accurately so we never switched again.
Reply With Quote
  #6  
Old 09-17-2013, 04:36 PM
Platinum Member
 
Join Date: Feb 2011
Location: Cincinnati, Ohio
Posts: 1,865
Re: Severely Dented Cases….Secondary Explosion Effect?

Quote:
Originally Posted by 307WYO View Post
Thanks for the input. I am leaning towards the idea the the powder charge is not burning hot and quick enough to fully expand the new case. I am going to try 92+ grains of retumbo tonight and see if that will work. It makes me a little nervous to shoot the rifle with light loads now, but i am not knowledgable enough on the subject to determine how dangerous this is...Thanks again

90 grns is listed as the minimum load...and if you load too light and the burn efficiency is all out f whack...you can get cases like you show AND WORSE. My Nosler manual shows loads of 92; 94 and 96 grains and says the 92 grain load was their most accurate
Reply With Quote
  #7  
Old 09-17-2013, 05:57 PM
Silver Member
 
Join Date: Feb 2008
Posts: 395
Re: Severely Dented Cases….Secondary Explosion Effect?

Saw this the first few weeks after the 7RUM came out, worked in a gunshop testing newly rebarreled rifles, we had no load data and this occurred on our handloads and a batch of factory Rem ammo.
We determined it was from too little an amount of slow burning powder, anything below around 90% case capacity would produce this every time even with bullets around 160gr.

You need to bump up that powder charge, because SEE is a very real possibility, we had instances where the report didn't go 'bang' but 'kerwhoomp', and we had to hammer open the bolt! This was with light charges and light bullets.

Cheers.
Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes


Current Poll
In the last 12 months, what was your longest rifle kill on big game?
0 to 200 yards - 25.96%
1,531 Vote
201 to 400 yards - 32.11%
1,894 Vote
401 to 600 yards - 23.09%
1,362 Vote
601 to 800 yards - 10.00%
590 Votes
801 to 1,000 yards - 3.92%
231 Votes
Over 1,000 yards - 4.92%
290 Votes
Total Votes: 5,898
You may not vote on this poll.

All times are GMT -5. The time now is 06:24 AM.


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