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Secondary Explosion Effect? Or.....?

 
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  #8  
Old 09-18-2013, 12:29 PM
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Re: Secondary Explosion Effect? Or.....?

Try sizing only 2/3 of the neck on the new cases, and no further.

If it were me, I would size the neck up to .308, then partial size most of the neck down to 7mm. This would create a false shoulder on the neck, to seal the neck in the chamber. This can also help if there is excessive head space present.
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  #9  
Old 09-18-2013, 08:42 PM
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Re: Secondary Explosion Effect? Or.....?

...
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  #10  
Old 09-20-2013, 09:45 AM
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Re: Secondary Explosion Effect? Or.....?

In addition to having that significant lip on the inside of the neck, the virgin rem cases are ALSO "wavery" around the neck's diameter, most likely a result of down-necking/annealing the 300RUM parent cases. You definately need to run virgin rem brass through the sizer/expander die [numerous times], BEFORE doing anything else to them, in order to get the neck diameter trued. And I would advise against trimming them. I just pulled a random sample of 5 virgin cases out of a box, and miked them up. They come up between 2.8425 and 2.845, while the spec indicates [max] length should be 2.850. You should strive to be as close to that as you can get, in order to get the best possible seal around the neck, for minimizing the possibility of any high-pressure gasses from getting past/behind it. If that inner lip really bothers you, try chamfering it out very lightly, making sure that the case does not loose ANY of it's length.

If that doesn't solve the problem, the fault must lie with the chamber, such as mis-alignment to the bore. If you still experience the phenomenon after trying all of the suggestions [including using hotter charges, for breaking in the cases], then HAVE THE RIFLE CHECKED OUT BY A SMITH.
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  #11  
Old 09-23-2013, 06:04 PM
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Re: Secondary Explosion Effect? Or.....?

I have not loaded a lot of Reloader 25. I did have some mysterious detonations with the .264 Winchester Magnum with R-22. I got rid of my two .264s before R-25 came out. I switched to the WSM case and tend to use Retumbo rather than R-25 with similar performance.

The Reloader 22 was leaving fumes in the barrel after firing in my .264 (again 2 different rifles). The fumes were detonating outside of the case with the next round if I did not blow out the barrel. I used a blast of canned air to clear the barrel. I had dents in the shoulder but not back onto the shank of the case. Compression would detonate the fumes when the case expanded to fill the chamber. Because it was a belted magnum, there was more room between the case shoulder and chamber. The Reloader 22 and 25 are Bufors powders with a lot of nitroglycerine and a lot of retardant to make them slow. I do not seem to have fumes from ADI Retumbo or Vithavuori powders. I will have some "Norma" 217 to play with tomorrow. It is the same powder Norma uses in the .30-378 Weatherby ammo. It does produce 3400 fps with 180 gr bullets, I have chronographed it my self. I do not know where it is made. I would guess it it a Bufors powder and may have similar problems.
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  #12  
Old 09-23-2013, 09:30 PM
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Re: Secondary Explosion Effect? Or.....?

Quote:
Originally Posted by 65WSM View Post
I have not loaded a lot of Reloader 25. I did have some mysterious detonations with the .264 Winchester Magnum with R-22. I got rid of my two .264s before R-25 came out. I switched to the WSM case and tend to use Retumbo rather than R-25 with similar performance.

The Reloader 22 was leaving fumes in the barrel after firing in my .264 .
I've never heard or seen this one, and I burn rl22 and rl25 by the keg in more overbore cal's than the 264. Sounds like something else going on with your reloads other than powder issues.

rl22 likes to build pressure rather slow if you don't have enough pressure and/or don't have enough load on it. Underigniting with a standard primer can do this too. The fumes( really smoke) have no more ignitability than air (the powder's already burned) so I'd suspect you are simply getting blowby occasionally on the next round.
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  #13  
Old 09-24-2013, 12:15 PM
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Re: Secondary Explosion Effect? Or.....?

My thinking is that for what ever reason the neck didn't hold those bullets securely allowing them to be dislodged by the primer. What's leading me to this is that the dents are right where the gas hole should be on your receiver, and (IF) the bullet exits the case mouth before preasure builds what would stop the gas from finding another exit (by leaking past the neck and shoulder to the gas hole). Pressure obviously went up at some point, you can see that on the case. Just a thought.

I think the issue lies with your new cases though. Maybe you might think about annealing the rest of that batch of cases, and resize them before you load any more of them.
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Keep in mind the animals we shoot for food and display are not bullet proof. Contrary to popular belief, they bleed and die just like they did a hundred years ago. Being competent with a given rifle is far more important than impressive ballistics and poor shootability. High velocity misses never put a steak in the freezer.

Joe
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  #14  
Old 09-24-2013, 04:41 PM
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Re: Secondary Explosion Effect? Or.....?

Any ideas as to how gas outside of a case would be higher than gas inside a case -to cause indention?
It's just hard to picture perfect local pockets somehow higher in pressure at any point of internal ballistics. Could it be powder blowing by? But then, why a pocket of it?

I can picture gas blowby preventing a case from good enough chamber grip, extending case length. But that's it.
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