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What`s happening here ??


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I had a few like this when I loaded a light load in my 7mm08. when I say light I only mean 42 grains as oppose to 45 grains of powder. Think it was something to do with the pressure being light and the case failing to swell to seal the chamber and subsequently the spent gases and powder **** get forced back and around the case - Could be wrong though...

 

 

M

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I had a few like this when I loaded a light load in my 7mm08. when I say light I only mean 42 grains as oppose to 45 grains of powder. Think it was something to do with the pressure being light and the case failing to swell to seal the chamber and subsequently the spent gases and powder **** get forced back and around the case - Could be wrong though...

 

 

M

 

Just about to say the same!

 

I have seen this recently with underpowered 3" .410 except that the case had been melted on the outside and not blackened.

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No homeloads, each weight of powder thrown and then checked and adjusted if necessary. I have to say again it seems to have only happened to these 4 and not since. Powder weight was in the mid range for n160 (can`t find my reload recipe book at the moment) so I am at odds to know why it has happened. I have shot 5 roe and a red since this and no sign of it. Cases were ultrasonically cleaned and hand sorted so they are highly unlikely to be from a faulty batch and were once fired full length resized fed classics :ernyha:

 

**EDIT** Also forgot to add, it is set up 20thou off lands with plenty of bullet still in neck!

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Just to go off in a slightly different direction was the case on the right the first to be fired?

 

Any chance there could have been some excess oil hiding somewhere in the action and making it into the chamber on the cartridges? Just an idea but perhaps it would have dieselled under pressure and given these results? You'd have thought the first ones would have done it though if that is the cause?

 

Usually I'd agree with the others and say a low pressure round but if they're hand loaded carefully that counts out that possibility!

 

EDIT... Anyone else find it strange that the markings are about half way down the case and pretty much the same on each one? If it was low pressure you'd expect it to be more uniform around the shoulder rather than a spot half way down? It really does look to me like the case is picking up a drop of oil in the same spot each time before being fed? I can't for the life of me remember if there were any cut outs in my Tikka action in that area and I don't have it to look at any more! :ernyha:

Edited by njc110381
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Never thought of that, I did oil it after cleaning and used the 2 rounds of shop bought ammo to "dirty" the barrel. It could have been that a drop or two of oil have made their way there after being set up in the rifle rest after firing the first two, as I remember it the dirt became less and less after each shot, cheers for that :hmm:

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On first inspection i would say:

 

Its insufficient obturation, very common with the 6.5x55. Sign of low pressure on most calibre's - but pretty common even on 6.5 loads that are running hot.

 

Things that possibly dispel that theory:

 

Your using the same round as always - which doesn't usually show these signs.

 

 

If its not doing it anymore i wouldn't worry. My old mans 6.5 always shows this (not quite so bad) and he is running a very hot load.

 

I think the oil in the breach is a pretty good call.

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