What happened

[Tokay444]

If you go back to your old die and brass, and your load comes back in line, you know it was either the brass, or the die.
Then introduce one variable at a time.

 

[bozo699]

If you go back to your old die and brass, and your load comes back in line, you know it was either the brass, or the die.
Then introduce one variable at a time.

Spot on!
Wayne

 

[Doom]

You changed 2 things. First is you have mixed brass so you may not have good consistency in capacity. You also changed dies so brass capazity may be slightly different from that. Depending on your original load’s tolerance for variations you may be out of the node. Just work up the load again.

 

[ppaul]

Assuming that " 3 rifles shooting the same ammo" was hornady brass, you still have 2 variables. 1, shot from different rifles and 2, your new whidden die. Since you've fired a portion of these in your rifle you have now eliminated that variable, so if possible build yourself 2 batchs of ammo with that brass say 20 with the "cheap rcbs die" and 20 with your whidden die. Go to the range and find your answer. Also if you want you could also load some of the "3 rifle" brass on your rcbs die might be interesting.