Ring around neck and soot on shoulders 6ppc

[Ccrider]

Trying to figure out what is wrong. I am getting a clean ring around the neck like it is sealing the chamber there and then soot all around the neck and shoulder.
This is from a .268 6ppc chamber shooting 68gr by bullets. 5 shot groups have been decent. Last 3 agged under .2.

My guesses are:
1) check to see if I am setting shoulders back too far
2) Necks may be too thick allowing for initial expansion and sealing at the mouth but not enough pressure to expand the remainder of the neck.
3) Could be under charged load but not in this case as I am using grs. of N133.

 

[INShooter]

I have had the same experience using some BT bullets with a short bearing surface. Went to 30+ grains of N133 and back to normal.

 

[mikecr]

What is your chamber end clearance, and neck clearance?

 

[Dusty Stevens]

Will a bullet slip into a fired case? All 133 lots are different- yours may need more

 

[Ccrider]

I have had the same experience using some BT bullets with a short bearing surface. Went to grains of N133 and back to normal.

Dang. You are spot on. I went to —-and it resolved the problem. However, I do not know what was causing the problem in the first place.

 

[Ccrider]

Will a bullet slip into a fired case? All 133 lots are different- yours may need more

No. I checked this and they will not. So, I took the necks down another .005 and tested 9 rounds. They will slip in and out now with your fingers. Just a little bit of friction.

 

[Ccrider]

What is your chamber end clearance, and neck clearance?

Finished round was .266-.2665. 268 chamber.

 

[INShooter]

Dang. You are spot on. I went to 30.1 and it resolved the problem. However, I do not know what was causing the problem in the first place.

The problem was low pressure.

 

[Ccrider]

The problem was low pressure.

That is what it seems like but how could there be low pressure with 29+ gr of N133 and a 68gr. bullet?

 

[jackieschmidt]

This is what a properly sized 6PPC or BR should look like. I shot this today. It’s sort of a sine wave.

I use an average .002 clearance for the loaded round in a confirmed .269 neck.

 

[Ccrider]

This is what a properly sized 6PPC or BR should look like. I shot this today. It’s sort of a sine wave.View attachment 1196072

I use an average .002 clearance for the loaded round in a confirmed .269 neck.

That is what I normally get. Don’t know why the change. I went through everything and could not find anything out of place. Loaded and shot a few rounds today. Everything was fine.

 

[mikecr]

Finished round was .266-.2665. 268 chamber.

So what is the chamber end clearance?

 

[Ccrider]

So what is the chamber end clearance?

.268 chamber, .003 clearance.

 

[Dusty Stevens]

I always run the neck turner over them after fireforming. You wont believe how inconsistent they are

 

[Ccrider]

I always run the neck turner over them after fireforming. You wont believe how inconsistent they are

I need to start doing this and will. Thanks

 

[Ggmac]

This is what a properly sized 6PPC or BR should look like. I shot this today. It’s sort of a sine wave.View attachment 1196072

I use an average .002 clearance for the loaded round in a confirmed .269 neck.

Has this barrel been set back ? Im seeing a similar ring at the shoulder, it appears to be the same length as the one on the neck .
Im glad the neck ring went away but the case pictures have me wondering.
Thanks , Gary

 

[Dusty Stevens]

One very important step is making sure the bullet slips in a fired case. Cant say that enough.

 

[Ccrider]

Has this barrel been set back ? Im seeing a similar ring at the shoulder, it appears to be the same length as the one on the neck .
Im glad the neck ring went away but the case pictures have me wondering.
Thanks , Gary

Yes. @Ggmac, what does the ring indicate?

 

[Ccrider]

One very important step is making sure the bullet slips in a fired case. Cant say that enough.

If the bulletin does not slip into the case, does that mean that the neck is too thick?

 

[jackieschmidt]

If the bulletin does not slip into the case, does that mean that the neck is too thick?

In most cases, yes.
In past years we were ate up on extremely tight clearances, thinking it enhanced accuracy. Much of that line of thinking come out of the old Houston Warehouse experiments when full length sizing and upper load window loads were non existent.

Most agree now that it is better to have a little too much clearance than not enough when it come to overall agging capability in the real world.