Need Help, ring on Brass - **Solved** See Pic on page 3

[Nellej12]

This is a new to me 284 Win. I'm seeing a very light ring on new once fired brass now that I relooked and last night on reloaded brass (2nd firing) the ring got bigger. You can feel this ring with your ringer nail. I used a paper clip to see if I could feel any ridge in the inside and nothing was noticeable.
The bolt would lift but I couldn't pull it back open with out a couple of light taps.

It's Lapua brass, using H4350 at 51.2 grains, BR2 primers.
I'm not over sizing, once fired brass measures base to shoulder: 1.8005 , I resized to: 1.7990
Primers look good.
Picture is of the reloaded brass.

Any Ideas would be helpful.




thanks,
Jeff

 

[MikeMcCasland]

Impending case head separation.

 

[Nowhere Man]

Are you sure you are not oversizing? I had similar issues with excessive head space. Take a resized brass and put a piece of tape on the back. See if you can close the bolt. If you can, you have too much headspace.

 

[jepp2]

Impending case head separation.

Not so sure in this case. But knowing more, like how much are you setting the shoulder back when you resize?

And incipient case head separations I have encountered are very easily felt with the bent paper clip. I flatten the tip on my paperclip to make it even more sensitive to the separation. Are you sure you started at the very bottom of the case with your check?

Lot of things can cause the bright ring in that area.

 

[Nellej12]

Are you sure you are not oversizing? I had similar issues with excessive head space. Take a resized brass and put a piece of tape on the back. See if you can close the bolt. If you can, you have too much headspace.

I rechecked my resized brass last night and 7 pieces all came out to the same measurement. 1.7990 I pushed the shoulder back only .0015

Too much headspace would make since because I see a very light ring on once fired brass.

I will try the tape when I get home today.

thanks!

 

[Nellej12]

Not so sure in this case. But knowing more, like how much are you setting the shoulder back when you resize?

And incipient case head separations I have encountered are very easily felt with the bent paper clip. I flatten the tip on my paperclip to make it even more sensitive to the separation. Are you sure you started at the very bottom of the case with your check?

Lot of things can cause the bright ring in that area.

View attachment 1057322

This is a raised ring. I'll cut a case open just above the ring tonight. Should set back is .0015

 

[philip brousseau]

i think your chamber is cut a little larger than the case head . unsupported case expands to fill chamber solid case head does not unless you are way over pressure.

 

[riflewoman]

It is NOT an incipient case separation.

It is either a sharp edge on the chamber or your die establishing a ridge on your brass. The direction you move your fingernail when you feel it will tell you.

 

[Milo 2.0]

I think this is where a guy should take a caliper or a mic to that area of a pc of new brass and once fired brass and go from there, do a sized case too to determine if the die is adding to it.

 

[Nellej12]

It is NOT an incipient case separation.

It is either a sharp edge on the chamber or your die establishing a ridge on your brass. The direction you move your fingernail when you feel it will tell you.

Well it's doing it lightly on new brass that hasn't been run through the sizing die. On the 2nd firing the line is raised and very noticeable.

 

[DOGCAPPER]

It is separating.

 

[Nellej12]

It is separating.

Not yet, its a raised ring. The brass in the pic has only been fired twice.

 

[wholman]

cut a case in half with a hacksaw.You will have your answer.

 

[spclark]

Chambers cut to a breech dimension significantly larger than the brass used in them, and/or the sizing die used to return them to a reloadable state, will see brass case walls moving back and forth laterally every time a case is fired and resized.

Case bases, being thicker across their diameter at the web, resist this. With too-hot loads though they will expand. Once they have, sizing dies won’t help a bit, primer pockets enlarge to a point they won’t hold new primers.

At that web/wall transition, radial brass movement weakens it causing what you may be seeing. It looks like a stretch mark, very similar to what incipient case head separation can look like, but usually without the telltale ‘ring of thinness’ a bent paperclip will reveal on the case’s inside wall. It’s not caused by case wall brass moving parallel to bore axis, but radially back and forth during firing/resizing cycles.

Extreme differences in chamber breech and case wall diameters just ahead of the case web may allow this to occur on the first firing.

 

[Richard Coody]

lots of things can cause that bright ring.

keep an eye on that base to shoulder datum. one firing might not even be fully fireforming that case. check at each firing.compare fired brass to sized and ensure shoulder bump is less than .002.

measure fired brass and sized brass diameter at the ring and compare. should be less than .002.

monitor the ring on the inside with the paper clip to ensure the brass is not stretching excessively at that location

 

[butchlambert]

I think it is a ring caused by a burr when chambering.

 

[madmixerman]

I had a similar situation with a 6bra . Upon the third firing it blew the back of the case off. Luckily I had safety glasses on. They now sport a big nick right in the center of the left lens, also drew some blood on the face and nose from shrapnel.The case looked like it was cut with a tubing cutter. Problem was the cone angle of the barrel was a little off. Be careful.

 

[butchlambert]

The cases that I've seen from casehead separation had a ring smaller in diameter, rather that this one, which is larger.

 

[M-61]

The bolt would lift but I couldn't pull it back open with out a couple of light taps.

That's an indicator. Light taps with your hand or.....?

 

[Nellej12]

That's an indicator. Light taps with your hand or.....?

Indicator of what? Light taps with my palm got the bolt open, I only fired these 2 reloaded cases in the pic. New brass has a very light ring in the same spot once I inspected them closer.