BRASS CASE CRUMBLED UP WHEN I SEATED THE BULLET

Caliber?
We're these FL Sized?
It looks to be that you are using combination seating/ crimping die, if so, was this round the first to be run through the die after you set the die?
From just observing the photo and not having any details, it could be construed that the bullet seating die was not set properly to the correct depth, the crimp was applied and there was still additional cammover left, and you applied it?

Do tell, was this on a single stage press, a progressive ? A single photo with no details will not do...now be a nice chap and spill the beans...

@50of4064 This is not the first die to go through the dies, I made a batch of 20 before this one.
The dies are old Lyman dies, perhaps they are seating/crimp, I will have to check it.
It is a single stage.

Thank you for the additional info...was this the first cartridge you ran through that seating die for that particular die install on you single stage press, for that run you were processing? Or was this the 4th or 10th, or 15th...trying to determine time-line of when failure occurred in relation to install of that die on to press. Process of elimination.
It was not part of the batch of 20 you spoke of, correct?

@50of4064
Nope it was after the first batch of 20, which worked and seated fine. The only thing different was the projectile was switched to a 150 grain.

Was this the 1st 150gr. Projectile you tried to seat in that batch?
And do you know why it crushed?

@50of4064 Yeah this was the 150 grain.
Most likely it was because the case was still too long after trimming.

I dont know that the seating / crimping dies' index off of the length of the case, or off the shoulder of the cartridge. I will have to check my dies' ..and better luck next time setting up your die, I know after something like that happens, one pays special attention to the setup of the dies'...the best to you and yours'