.338/300 rum (edge)

[huntintoo]

What caused this separation? I suspect case OAL being too long, and the Berger 300 grain Hybrid being on the lands and groves? Just looking for an oppinion? I know every one has one:-D!
The damage to the brass shoulder was also caused at the time of firing, not on the extraction.

 

[barnesuser28]

Case head separation, caused from sizing the case too much. How many times fired? How far have you been pushing the shoulders back on each firing?

 

[huntintoo]

5th reload 86.5 grains of IMR 7828, 2808 Ave fps. 93rd shot from the rifle. Neck sizing about 90% of the neck with a .338 RUM die backed out to do most of the neck.
I jus got .338 Edge dies from Redding and have used them but due to this case being stuck in the action I have not shot any of the FL sized reloads yet.

 

[huntintoo]

I'm unsure about "pushing the shoulders back"? can you explain?

 

[barnesuser28]

When the case is fired a couple times it usually is a slight crush fit to the chamber, bumping the shoulder of the brass will make the case go into the chamber without resistance. The shoulder is usually pushed back .001-.002" from when it would touch the shoulder of the chamber. If you are only neck sizing you probably arent moving the shoulder at all. Clear as mud? My guess would be you have way to much headspace on your rifle, who chambered it?

 

[huntintoo]

I had a gunsmith chamber it for me. And none of the other 92 rounds fired from it have had any problems. Thats why I'm a little perplexed.
I was told the Berger bullets like the lands and grooves and loaded for such. .001 of of them. But my groups went to .33" at 100. so I was hopingto keep the load.
I have some others that were faster but if I started getting around 2850fps they(groups) were opening up on me.

 

[GWS]

Are you annealing the brass? This type of separation can be an over annealed case and a heavy bullet pulling the case apart. My Edge works the brass pretty hard and annealing does help extend the life. I use a Benchsource annealer and only anneal the neck and top of the shoulder then neck size with a bushing size die. If you do not anneal it could be simply metal fatigue from over working the brass.

GWS

 

[huntintoo]

I have not annealed any brass yet. I wanted to see how many loads O could get and compare. I have 10 brass with 5 loads on them. This is the first. I pulled the bullets on 3 to check the inside for signs of scoring. Unsure if I dare shoot the others?

 

[Firetec]

If it has only happened once then it may have just been a bad piece of brass. If it keeps happening I would try running a different brass and checking the headspace. I ran into this issue with a Weatherby.

 

[huntintoo]

I guess I'm gonna have to p ut on my big boy pants and try her again!

 

[Deleted member 46119]

I know annealing helps.

338/300 RUM is still being built.

300WSM throwing 208s is on 18th firing. Annealed often.

Weatherby, same same.

I have been told that R-P in the 338/300 RUM has a limit of 4 firings but it is a primer pocket issue not head separation.

 

[huntintoo]

I have annealed 300 H&H brass to make 300 Wby but it was a drastic shoulder change. Did not think it was needed for a neck only change. Stands tp reason it would make themy brass last longer. I'll be letting y'all know how it turns out.
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