Dented 6 XC cases.

S

Stefan Karlsson

Guest
I chambered a 6 XC for a good friend a while ago. It's a Barltlein barrel chambered with a Kiff reamer .269 neck.

Some cases show signs of low pressure and even have dents in them. This shouldn't happen with the loads he uses! Primers show normal pressure, in the upper region. He uses 105 gr Berger match and a load of about 35 gr Norma 203-B (pretty close to N-150).

I have not seen a thing like this besides in cases where the load have been way down in pressure.

Any ideas?

/Stefan
 

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Usually, on firing, the case neck expands to seal the chamber. Looks to me like this isn't happening, so pressure is causing the dents. Not sure why. I'd suggest your friend go over all the finished/prepped case dimensions again.

Happend to me once or twice in a 6.5/06 Ackley, and I never could figure out why. I'd suspect that for those cases that fireformed well, the problem won't happen on subsequent firings. That was my experience, anyway.
 
This happened to me with a 7mm RUM. Was using RL 25. Called Alliant, they didn't know. Called Hodgdon's, they didn't know. Then I recalled the Ballistisions notes at bottom of page in the Nosler number 6 reload manual that says: periodic case neck annealing may be required to prevent case blackening or collapsing. I annealed and that was that

Side note, that rifle was a Sako Deluxe with a Leupold LR 6.5x20 that I foolishly sold to Cabelas Gun Library. If anybody comes across it grab it or contact me so I can... :eek::p
 
Norma 6XC-37.6 gr maximum with 105 gr Berger

Powder charge is below starting listed here. http://www.norma.cc/en/Ammunition-Academy/Loading-Data/Norma-6XC/ Cause is low pressure, to light neck tension, very little bullet in the case neck (if long throated). Maybe try a faster burn rate of powder? This is my guess? :)
257Weatherby.jpg
http://thefiringline.com/forums/showthread.php?p=4928827#post4928827
 
Pure speculation:

In order for the case to be dented, the pressure outside the case has to be greater than the pressure inside. That seems to imply that the base and neck would have to be sealed to the chamber. Since the base of the case looks shiny, it seems it wasn't exposed to propellant gas and was sealed. But how do you get high pressure gas outside the case AND seal the neck? It seems like you would have to have as situation where the neck was not sealed, then sealed and remained so until the chamber pressure dropped enough to cause the dent.

How on earth that happens is beyond me, but I bet it has something to do with neck hardness and clearance.
 
use more powder

35 gr is aprox 5 grains too light,,,,the results show it as wayyyy too low of a charge,,,,Roger
PS...I use aprox 39 gr of 150 in my 6mm 250 AI with 105's.....and I have jumped bullets .150" with various hunting ctgs over the years and only time such case dents were seen was with a powder charge either too low or powder too slow of burning rate,,,,,

OP,,,,find out what the max load is and work from there,,!!!!!.....dont piddle around with 75% loads,,,,
 
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35 gr is aprox 5 grains too light,,,,the results show it as wayyyy too low of a charge,,,,Roger

40 gr of Norma 203-B in a 6 XC with 105 gr bullets!? That´s a pretty stiff load!!

I have talked to the guy with the rifle and it seemes like the troat is cut a bit long (misstake by me). My 6 XC reamer is without throat and it looks like I didn´t pay attention enough while cutting the throat.......

I have seen signs of low pressure in 6,5x55 rifles when pretty hot loads have been used with medium rate powders and bullets seated far out in the necks to chase the lands. Most 6,5x55 rifles comes with extreme long throats. I have never seen the dents in these 6,5-examples though. The problem could be that the bullets have to be seated far out to get to the lands and the pressure doesnt build up fast enough as a result. We will try to shoot a few rounds with bullets seated at least half way down the neck and se if the problem still exist. If that cures the dent-problem I´ll just cut a new chamber and pay close attention to the throat and the problem should be gone!

The barrel is long and with a heavy profile so a new chamber will not ruin the rifle!

Thx for the inputs guys!
 
Could it be grease or some type of solvent in the neck or chamber body causing the dent.
Have done that when I didn't swab out chamber.
 
Dent

Speer Manual number 8, page 57, has a photo & explains the dent. More or less what i said above. May or may not be the problem? :confused:
 
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