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primers

BW64

6BR primer problem. Primers are raised somewhat after firing. Just put on a new barrel & breaking in with some low speed loads. Any help would be appreciated. Trying to get pic from my phone.
 
Seat bullets out to engage grooves, your fireforming I presume, seat bullets and get a good feel on bolt close a tad tight, the primer is coming out and then brass hits boltface I think primer is flowing around FP I could be altogether wrong... I would seat bullets out but just make sure boltface isn't worn from washout also
 
BW64 said:
View attachment 1675988got it
Click to expand...
Uh-Oh…! That does not bode well for your bolt face and firing pin hole..
Measure base to shoulder on those fired cases and see how much they have grown compared to the loaded ammo.
It is possible that you new barrel’s chamber has lots more head space than previously and your current shoulder bump is too much.
The extra space is allowing the case to blow out to fit but during the firing it is loose enough that the primer is backing out and then being pushed back into the case but during that moment in time the gas is escaping and that is why you are seeing the flow marks. De-prime a case and see if the primer pocket now has very slight groves cut into it from the escaping gas. If so, then the case is scrap….
Take 6MMsteve’s advice and seat the bullets long enough to engage the lands to stop any jump of the case if your ammo is showing too much shoulder bump as that will take up the gap and keep the case tight against the bolt face.
I only bump my 6BR cases .0015”, just enough to comfortably chamber, same with neck tension as that has proven to be enough tension to hold the bullet securely and makes seating force more consistent for me.
 
Fire Dog said:
Uh-Oh…! That does not bode well for your bolt face and firing pin hole..
Measure base to shoulder on those fired cases and see how much they have grown compared to the loaded ammo.
It is possible that you new barrel’s chamber has lots more head space than previously and your current shoulder bump is too much.
The extra space is allowing the case to blow out to fit but during the firing it is loose enough that the primer is backing out and then being pushed back into the case but during that moment in time the gas is escaping and that is why you are seeing the flow marks. De-prime a case and see if the primer pocket now has very slight groves cut into it from the escaping gas. If so, then the case is scrap….
Take 6MMsteve’s advice and seat the bullets long enough to engage the lands to stop any jump of the case if your ammo is showing too much shoulder bump as that will take up the gap and keep the case tight against the bolt face.
I only bump my 6BR cases .0015”, just enough to comfortably chamber, same with neck tension as that has proven to be enough tension to hold the bullet securely and makes seating force more consistent for me.
Click to expand...
OK So they grew from 1.158 to 1.164. Too much right?
 
BW64 said:
OK So they grew from 1.158 to 1.164. Too much right?
Click to expand...
.006” is a fair amount of stretch, especially for un-annealed “Fired a few Times” brass.
That gives the case plenty of room to have a jump in the chamber before the case expands to fit the chamber and .006” is enough room to have the primers blown backwards allowing the gas leakage and the final expansion to reseat them.
Have you checked the primer pocket now ? How do they look?
The photos show gas leakage up the sides of the pocket and that generally means that you will find erosion groves in the sides of the pocket and that means toss those ones into the scrap brass bucket at the range.
The other thing to look out for is neck splitting due to work hardening and then having to stretch so much to fill the chamber.
New brass will have a softer neck and shoulder as they come annealed and can tolerate the stretch easier and quicker but again setting the projectiles to at least “touch” will hold the case tight against the bolt face and making sure that the primer is held in place when fired.
 
BW64 said:
Yes the primer pockets are shot. So should I adjust head space at least .003 or 004?
Click to expand...
For sure, I would never run more than .002” bump, especially since you are not annealing the cases and they will be a bit work hardened and resisting stretching to fill the chamber when fired.
It appears that your current loaded ammo is just too short for the chamber and that is allowing the primer to back out under the pressure of ignition and then when the case finally expands enough to fill the chamber the primer is forced back into the case but the damage due to the escaping gas has now ruined the case and is also damaging the face of the bolt and firing pin hole. Losing the brass is one thing but having to have your bolt repaired will be costly…
 
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