That isn't good.

[BRTreedogs]

Ugg,
Could be worse, atleast your on a way to a solution

 

[elkguide]

At least you have the entire case in your hand. Be thankful for that. When they separate and only half of the case comes out, then "Houston" really has a problem.

(Don't ask me how that I know.)

 

[BRTreedogs]

I wheeled and sealed on some ammo once, had to have frame on my glock replaced.
Lucky to have my fingers and eyes.

 

[Cahunter805]

Everyone is correct, the dies in their current setup are the main issue. Had the rifle over to the Gunsmith/Custom Rifle Builder and after inspection of the rifle and the brass it was concluded that these dies, when installed in the press as instructed, are pushing the shoulders back too far.

Guess who gets to pull bullets and load new rounds now? Not the end of the world, I like doing it. Have to get a piece of once fired brass first to set the dies up where they should be.

Glad everything was confirmed. Personally I’d just go buy some new brass and rework your load a bit. You can setup your FL die to just straighten the necks on the new brass and not even touch the shoulder then load them and work up from there. Then you will have once fired brass after your initial load tests and can setup the die correctly to bump the shoulder .002. Then set the lock ring.

 

[4ester]

I’ve was down this same path last year with a 300 RUM.

Came to the conclusion that I was bumping back the shoulders too far and creating excessive headspace. After 5 firings I had a case separate. Glad it was at the range and not in the field.

I try and hit that .002 bump anymore.


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[KineKilla]

I set up my die to take the case from 2.121 to 2.119. I bumped them back and checked fitment in the rifle chamber until it closed with just a bit of firm pressure. The bolt would close at 2.120 and was a bit too easy at 2.118

Unexpected thing though as I worked the die down a little at a time was that the case actually grew prior to going back down.

Guess that's the brass stretching? Or the case mouth getting longer as it gets resized?

I meaured a small sample of new unfired brass and found that they are around 2.10. That makes for quite a bit of stretch on that first shot.

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[MrTim]

Had the exact same experience with that cartridge using Hornady brass. I have 10 loadings on one batch of Hornady brass. But on the most recent batch I’m getting case head separation on the 3rd loading with the exact same load, no changes to the die setup. I concluded that the brass quality must be inconsistent.

 

[tdot]

I set up my die to take the case from 2.121 to 2.119. I bumped them back and checked fitment in the rifle chamber until it closed with just a bit of firm pressure. The bolt would close at 2.120 and was a bit too easy at 2.118

Unexpected thing though as I worked the die down a little at a time was that the case actually grew prior to going back down.

Guess that's the brass stretching? Or the case mouth getting longer as it gets resized?

I meaured a small sample of new unfired brass and found that they are around 2.10. That makes for quite a bit of stretch on that first shot.

Sent from my SM-N976U using Tapatalk

That case growth is caused by the compression of the fired brass from the diameter of your chamber down to the die, which results in brass being forced forward, as that's the only place it has to go. It's a common sign if you are sneaking up to a final resize dimension like you are doing.

 

[Cahunter805]

I set up my die to take the case from 2.121 to 2.119. I bumped them back and checked fitment in the rifle chamber until it closed with just a bit of firm pressure. The bolt would close at 2.120 and was a bit too easy at 2.118

Unexpected thing though as I worked the die down a little at a time was that the case actually grew prior to going back down.

Guess that's the brass stretching? Or the case mouth getting longer as it gets resized?

I meaured a small sample of new unfired brass and found that they are around 2.10. That makes for quite a bit of stretch on that first shot.

Sent from my SM-N976U using Tapatalk

If your using standard RCBS dies then the growth is very typical. Those dies size the neck small and then use the expander to push it out on the down stroke of the press. Can create some runout. I prefer Redding bushing dies.
Sounds like you have the shoulder bump setup. Should be good to go but I’d still consider some better quality brass if the gun is shooting well also.

 

[KineKilla]

I wish Lapua made 7mm brass but they don't. My rifle builder says they have good experience using Norma brass.

If you base quality off of price then Norma or Nosler Custom would be the best two sources.

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[wind gypsy]

I wish Lapua made 7mm brass but they don't. My rifle builder says they have good experience using Norma brass.

If you base quality off of price then Norma or Nosler Custom would be the best two sources.

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^ This is where I'd start for brass. Norma is probably good as well.

I set up my die to take the case from 2.121 to 2.119. I bumped them back and checked fitment in the rifle chamber until it closed with just a bit of firm pressure. The bolt would close at 2.120 and was a bit too easy at 2.118

Sounds like you got er figured out. I have found that when trying to run absolute minimum shoulder bump you end up with a few cases that are a bit tight when closing the bolt. To me that is a sign to bump them a bit more. 3 or 4 thousandths isn't going to kill you, especially when compared to 20 thou.

 

[BassAssassin04]

I've had that happen with hornady brass in my 270. I just avoid hornady brass now.

 

[gbflyer]

The lot of Hornady brass I got for .300 H&H was .030 short of headspace. Not the belt, but the base to shoulder. The Norma brass lot I have is within .004. The Winchester is within .001. These are new brass dimensions. I build a stub gauge with the same reamer every time I chamber a barrel so these measurements are accurate. The Hornady separated on firing #4. I use a .002-.003 bump, it’s a hunting gun and I want it to feed without issue. I tossed the Hornady and will not be buying any more of it. It’s a one time use proposition for this cartridge.

 

[BRTreedogs]

I'd consider hitting up @Unknown Munitions for some ADG
Or @Ryan Avery for some bertram.
If ether 1 makes 7 mag, idk?

 

[Wapiti1]

The way to make belted brass last the longest is to run a fireforming load using a light powder charge with the bullet seated into the lands. Don't size new brass, only uniform the case mouth, load with a light charge, seat .005" into the lands, and shoot.

This forces the case head against the bolt, and you get no stretch at the web. Only the shoulder moves forward.

Then you set up your die to either barely bump the shoulder, or come up a tad short (bolt will be hard to close, though). Neck sizing is the other option, and the one I use. Anneal the neck every 3-4 loadings.

The most damage is done to the brass on the first firing if it is allowed to stretch at the web.

Jeremy

 

[MeatBuck]

Op hit panhandle precision on YouTube bud. Sounds like you may benefit from watching the precision load development series.

Reading things here that he covers in the load development series.

Tons of good info there

 

[MeatBuck]

Doesn't Norma make Noslers brass?
Thought I read or heard that somewheres.

 

[Sawfish]

Well, it a lesson that you will remember.

 

[LaHunter]

I set up my die to take the case from 2.121 to 2.119. I bumped them back and checked fitment in the rifle chamber until it closed with just a bit of firm pressure. The bolt would close at 2.120 and was a bit too easy at 2.118

Unexpected thing though as I worked the die down a little at a time was that the case actually grew prior to going back down.

Guess that's the brass stretching? Or the case mouth getting longer as it gets resized?

I meaured a small sample of new unfired brass and found that they are around 2.10. That makes for quite a bit of stretch on that first shot.

Sent from my SM-N976U using Tapatalk

You actually want the bolt to close easy. That "bit of firm pressure" means you are putting the brass into a bit of a bind. When your brass is properly sized, your bolt should close easily. The best way to determine this is with your firing pin removed and the ejector plunger removed. Alex Wheeler has some great youtube videos on how to do this.

 

[KineKilla]

It closes with a bit of pressure on brand new, unfired brass. Takes a bit of pressure to compress the ejector pin.