6mm Creed Case Failures

[Carlos Danger]

Hoping someone can shed a little light on this. I'll give as much detail as possible before asking for your input.

Just starting noticing these failures pop up about a month and a half ago. First one, then another this weekend, but also catching serious signs of obvious pre-failure. These are occurring in almost exactly the same location on each case. This is the second brand of brass I've reloaded so I have little point of reference other than to say the Hornady brass I've used never displayed this.

Current Info.:

1. Starline large primer brass.
2. Probably 5-7 reloads on them. (I should keep better records)
3. I've started tossing those that are dropping primers.
4. Annealing almost every cycle.
5. Full length with Hornday dies.
6. Low charge of 38.0g H4350 with 115 DTAC's or 110 SNK's. I don't run anything hot.
7. Federal GM210 Match primers.
8. Ruger Precision with Bartlein 26" barrel (White Oak)

My rifle season is coming to a close soon so planning on new brass in the coming months. I'll just be running these until end of season. When they do fail, case removal isn't a big deal. Upper portion typically drops out easily or with use of a rod / brush. Just wondering if this has been seen before, inherent to the manufacturer, a bad lot, etc.? Thanks in advance.

 

[TxWelder35]

How far back are you bumping the shoulders with each sizing?

how much did they grow from new to 1x fired?

 

[Supersubes]

That’s called a case head separation. You’re oversizing the cases. Stop shooting them.

 

[Powder_Burns]

Use or make a comparator gauge. I take a 9mm case and zero my calipers with the 9mm case on it. Then take a fired piece of brass and put the 9mm case over the neck of your 6cm case and measure the distance from the base to the shoulder with it. Then do the same with a resized piece of brass and see what the difference is. You want to adjust the die so you aren’t pushing the shoulder back more than .003”. Retire that whole batch of cases that are showing separation.

 

[Carlos Danger]

How far back are you bumping the shoulders with each sizing?

how much did they grow from new to 1x fired?

I'm sizing cases back between .001-.002" max. Same as I've been doing all along.

 

[lash]

Can you show us Pictures of the measurements of both the fired case and the sized case?

With only 5-7 reloads on these cases, it doesn’t seem possible that there is that much material moving to cause case head separation if you are only bumping the shoulders 0.001-0.002” each time.

 

[Powder_Burns]

Maybe too much annealing going on and the body is getting softened up too.

 

[TxWelder35]

Wondering if there Is excessive headspace on the rifle and the brass is growing a crazy amount on the first firing.

 

[918v]

Wondering if there Is excessive headspace on the rifle and the brass is growing a crazy amount on the first firing.

that’s what I’m thinking too

 

[ShtrRdy]

Cut a case open to see if the wall thickness is just thin or if the brass has been stretching.

 

[TX_Dan]

Or use a paper clip with a bent tip as a feeler. You’ll feel it catch if it’s ready to separate.

 

[308pirate]

I'm sizing cases back between .001-.002" max. Same as I've been doing all along.

Can you show us Pictures of the measurements of both the fired case and the sized case?

With only 5-7 reloads on these cases, it doesn’t seem possible that there is that much material moving to cause case head separation if you are only bumping the shoulders 0.001-0.002” each time.

I'm having the same exact problem with Winchester 308 cases. I have Lapua cases with over 8 firings and I have never, ever had a failure.

I'm bumping the shoulder back .002 and I measure with the same Stoney Point HS gauge and calipers that I've been using for the last 20 years. I've been working in mfg shops my entire life so I know how to inspect parts, find datums, and use calipers.

Sometimes brass is shit from the manufacturer.

 

[lash]

I'm having the same exact problem with Winchester 308 cases. I have Lapua cases with over 8 firings and I have never, ever had a failure.

I'm bumping the shoulder back .002 and I measure with the same Stoney Point HS gauge and calipers that I've been using for the last 20 years. I've been working in mfg shops my entire life so I know how to inspect parts, find datums, and use calipers.

Sometimes brass is shit from the manufacturer.

I can’t argue with that. I once had a very large quantity of SSA .260 brass that after about three mid speed loadings, started losing primers. I sold the whole huge batch to a guy here that just wanted throwaway brass for his semi. What a waste.

 

[Carlos Danger]

Just measured recently fired Starline brass compared to unfired Prime ammo. My fired cases measure 4.5-5.5 thousandths longer. Seem like headspace is a little too long or within acceptable tolerances?

 

[lash]

Just measured recently fired Starline brass compared to unfired Prime ammo. My fired cases measure 4.5-5.5 thousandths longer. Seem like headspace is a little too long or within acceptable tolerances?

I’m confused a bit. I thought that you said that you are only bumping your cases back 0.001-0.002” each time. How does you current headspace compare to the original headspace of this brass? What are the actual base-to-shoulder measurements of the unfired Starline brass, the unfired Prime ammo and the fired Starline brass?

 

[TheOfficeT-Rex]

Just measured recently fired Starline brass compared to unfired Prime ammo. My fired cases measure 4.5-5.5 thousandths longer. Seem like headspace is a little too long or within acceptable tolerances?

I'd expect factory ammo to be on the shorter side of headspace tolerance - makes it easier to fit most factory chambers.

ETA chamber drawing.

 

[lash]

Also, what are you using to measure headspace?

here’s a spec:

 

[Carlos Danger]

I’m confused a bit. I thought that you said that you are only bumping your cases back 0.001-0.002” each time. How does you current headspace compare to the original headspace of this brass? What are the actual base-to-shoulder measurements of the unfired Starline brass, the unfired Prime ammo and the fired Starline brass?

Sorry. Maybe I'm creating the confusion. Being a noob I never measured original brass headspace. I guess what I'm trying to show would be the difference to what a fired case measures compared to what I would expect SAAMI brass would be unfired with the Prime ammo. Next batch of new bras will receive more attention. I headspaced this barrel with go / no gauges and had no issue chambering my brass.