Soot on the case body?

[SavageLapua]

I was out at the range on the weekend printing groups with my Tikka T3 6.5x55 Swede (love this thing) and during my 3rd sting I noticed the case pictured below. It still printed it's usual 0.5MOA 5 shot group.

Load:
Virgin Lapua brass (neck sized)
CCI250 Primer
47.5gr RL22
140gr SMK
2720fps

Sorry about the poor quality (phone camera) I tried to capture the soot in the extraction groove.

I haven't seen this before and it has me concerned... I'm not sure what the issue could be. If someone could point me in the right direction, it'd be greatly appreciated.

Thanks,
SL

 

[Reloader222]

One of 2 problems I guess:

1) Shoulders sized back too much;
2) Neck tension not enough to enable proper expansion of case body and thereby resulting in gas leak.

Annealing the cases also essential to enable proper seal.

 

[benchracer]

It's virgin brass and Lapua brass is factory annealed, so I don't think that is the issue.

Likewise, the case neck is not being smoked, which would seem to indicate that there is sufficient pressure to seal the chamber.

I am not sure where the soot is coming from, but I am not inclined to believe there is an issue to be concerned about.

 

[RT2506]

Could be the virgin cases have the shoulder pushed back a little too much for your chamber and thus some gas is getting past the shoulder before it expands enough to seal the chamber. This is just a shot in the dark. I would try cases that have been fired once and neck sized to see if this goes away.

 

[g0rd0]

I agree with RT2506, load it up again and see if it sorts its self out

 

[Lefty7mmstw]

Slow powder and moderate powder capacity; I'd bet your peak pressure isn't coming on fast enough to seal the chamber before the bullet clears the neck. Faster powder or more charge/pressure would likely fix this. Closer brass dimensions to your chamber as previously mentioned would help too. You already have plenty of primer though....

 

[Clever]

All the suggestions are Great. But I see you are using CCI#250 as primer.. I am an avid magnum caliber shooter.. the CCI#250 is a Magnum primer, your caliber is not. Try the CCI#200 or FED210, should resolve your problem. YES I know you could use Mag primers instead of regular primers in some cases.. But 6.5X55?

 

[SavageLapua]

Just an update, I did a thorough cleaning of the barrel and chamber last week and went to a shoot on the weekend. It seems to have cleared up the issue. Thanks for all the suggestions guys.

Clever, I said the same thing when the original owner gave me the recipe for this rifle. I've tried a couple different powders and different primers and the slower powders with magnum primers are giving me the most consistant numbers with the lowest ES and SD.

SL

 

[Clever]

Just an update, I did a thorough cleaning of the barrel and chamber last week and went to a shoot on the weekend. It seems to have cleared up the issue. Thanks for all the suggestions guys.

Clever, I said the same thing when the original owner gave me the recipe for this rifle. I've tried a couple different powders and different primers and the slower powders with magnum primers are giving me the most consistant numbers with the lowest ES and SD.

SL

Nice, a buddy of mine uses H4831 with CCI200 PRIMER. Great results. Good Luck.