Lesson Learned

[Gbro]

I was out of cartridges for my .257 Robt's and had an opertunity to take a reletive shooting (unplanned, and we shot muzzle loaders last visit).
Well I rather haistily loaded a batch of 117 gr. Hor. SST's with 43.5 Gr. IMR 4350 COL 2.875
Now I have always used .040 backout on my dies for this rifle and by doing that I have a little bolt drag upon closing the action. I am shooting these in a M77 Ruger ultralight.
After shooting a couple rounds I turned the rifle over to my niece. After her second shot she was unable to close the bolt. It would only close the action about 1/2 way. On the floor of the shooting line I saw what looked like a 45 ACP case?? Having a clean floor as always at our range I was quite puzzled?
This is waht I found,
The top case is a 30-40 Kraig that I used to recover the second half of the broken case. The middle is from her 1st shot.
Now Like I said, This is a lesson learned from my loading practices that I must admit are a little rusty as I have not been loading as much as years back.
I am looking for confermation on what I( believe) is the cause of this case failure/reloading error.
Thank you,
Gbro

 

[44 AMP]

Case separation. How many times did you reload that case? How many times have you trimmed that batch? Not certain if you actually have a reloading error other than not keeping count and checking to see when the brass was getting worn out.

Take some of the fired cases and do the paperclip check on them, to see if all that lot is about had it, or if it was just that individual case that failed before the rest.

Usually the separation is right above the case head, but as you can see, not always.

 

[Gbro]

OK,
I did a little more researching on these cases. This batch is from 1992 and when I pulled the bullets out of the entire batch to check them with a paper clip.
One separated 3/4 around just by whacking the bullet out and one more has a shinny ring in the same area as both the others and the paper clip confirms this is a weak spot.
AMP you are spot on with the batch of brass is worn out.
Another thing I realized when I deprimed the cases is I had full length re-sized all my reloads the last couple years because the grandsons were having trouble closing the bolt on some of the neck sized only loads that I have been shooting for years.
So I believe that my brass is old and hard and by F L Resizing caused these cases to fail where they did.
And Yes I had some that were right at the max length and needed trimming. This is what I had thought was my error when I started this post, as I thought that after neck sizing the way I was (Until I had bolt closing interference) that I didn't have the luxury of letting the cases go to the max and that I had always up till the last 2 years trimmed them every other loading.
New brass on order and full length resizing at least until I get a neck size die for this rifle.

Gbro