powder sine wave on case neck

chajam

chajam

Member
EE Expired
Rating - 100%
1   0   0
Location
Carlyle, Sask
I noticed what looks like a sine wave of powder around the neck of my 6mmbr cases, anyone ever see this , is it good, bad or does it really matter.
 
:)Well, I think the common consensus is that the round did not produce enough pressure to expand the brass enough to seal the chamber and gases/soot get deposited on the neck of the case.

Don't know about any sweet spot.;)
 
I got this on some .270 rounds I didn't neck-size tight enough. After turning my mandrel (was using Lee dies), the necks hold the bullets a bit tighter and don't put any more soot on the necks. The reason yours are getting soot might be different, thought I'd just share what fixed my issue.
 
Sine wave type residue on the necks of the brass is good.

I get them all the time and I am using hotter than recommended loads in two of my rifles so it is not due to under pressure loads as some have suggested.

See pics I posted in THIS THREAD
 
Last edited:
I am more inclined to think it's neck tension. I am using 30+ varget with cci450's and 105 vlds at 2800+ fps . I am using a .270 bushing, I cant push the bullets in with my finger but I know lots of guys using .267 and .268 bushings. I thought accuracy was supposed to be better with moderate neck tension.
 
Possibly because of light neck tension, the bullet moves forward before a lot of pressure is generated and some unburnt powder leaks past back around the neck before it seals.

Another factor might be that the cases have been reloaded a number of times and the necks have been work hardened, meaning that they will need a slightly higher pressure in the case to seal. Again, this might let a bit of unburnt powder past before the neck seals. Solution would be to anneal the case necks.
 
Last edited:
You must log in or register to reply here.
Back
Top Bottom