HELP-HELP HELP !!!!!!

[soup]

FOLKS,
I have a 20" SS Contender barrel made by Bullberry in 22K HORNET. While fireforming brass the barrel shot SUB MOA. Now that I am using the proper brass the groups have opened to 1.5" & I got a FEW misfires.
I used 12gr LIL GUN small rifle primers-35grVMAX. This barrel shot sub moa before I got it , so I know it is capable. It was made for the TCA 20th anniveersary bash by FRED SMITH himself & donated to the TCA. I won it in a raffle. They shot a couple of hundred rounds thru it at the bash & it was SUB MOA !!!!!
I'M DOING SOMETHING WRONG !!!!...Can anyone help here ??I use a set of Redding Deluxe dies & I have not used the neck sizing die at all.
Thank you in advance for your time & help.
SOUP

[Grumulkin]

I have a couple of questions:

1.  Are you using the same load and the same primers the cases were fireformed with?

2.  When you resized the brass, did you neck size or full length resize?

3.  Are you using the same load/primers/cases that good accuracy was obtained with initially?