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Powder burn pattern/ring on necks

Active Member


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Hi All,


Belly or anyone for that factor, 


I remember you showing me the necks of your new BRA case and the powder burn ring on the necks and discussing the ring stopping a little high maybe meaning you were a little tight. 

did you find any correlation to the depth of the burn ring and accuracy. Hence getting that burn ring down to a certain point on the neck but not right down to the shoulder and see improvement.


i have a mixture of cases showing different depths all shooting relatively good for me on the 284 (not sure I’m good enough to shoot the difference) and wondering if I should aim for a more uniform ring.

I guess this is on the back of watching a few Bruce Tee videos and listen to his theories on the matter.


Dave Z




Topic starter Posted : 29 May 2024 6:18 pm
Active Member

Hi Dave,


I looked at this too, briefly, I found that consistent annealing seemed to uniform the carbon mark because the neck and shoulder area became a bit more malleable. I could not discern any difference in accuracy though. If you are not close to max on your charge, you could look to finding the next node up with a little more powder, that might reduce / uniform the ring if it bothers you because this might expand the case marginally quicker resulting in a tighter seal.



Posted : 1 June 2024 8:11 am
Michael Bell
Member Moderator

G'day Dave,

I remember the conversation.

I was talking about Tony Boyers theory regarding carbon marking on the necks of cases after firing.

In his opinion "if there's a clear horizontal line of carbon going all the way around the middle of the neck after firing, then the neck's too tight and may be causing unexpected flyers. A wavy pattern indicates that, as the bolt lugs settle on the receiver lugs, the brass has contracted enough for some gas to escape."

He goes on to say "if you have very well matched lugs and straight brass on a 2 lug receiver you will see 2 dips in the pattern, if it's a 3 lug you will see 3 dips".

He also says that this pattern will indicate if the cases are too thick but will not give any indication if the necks are too thin!

I have certainly seen these patterns on the new BRA's I'm working on and turning a little more off the necks does exactly as he explained.....it also seemed to sort out the unexplained flyer thing!

I can't say it was as obvious on the short necked BRX's I have in the stable which suggests neck length makes it a bit easier to read.


Prior to commenting on the carbon pattern he did say that after firing the cases a few times you should be able to insert a bullet into them before sizing. If the necks are too thick this will most likely not work.....

Seems to me this might be the better and easier method to follow.





PS. The Book of Rifle Accuracy by Tony Boyer is a great read and very relevant IMO

Posted : 1 June 2024 9:28 am
Active Member

thanks guys 

I may just seperate these cases that look like they show gas escaping down to the shoulder Vs the ones that show a good seal and see if I can notice any difference. 


Topic starter Posted : 2 June 2024 8:33 am