After you have ruled out the dies as the problem, take one of the offending cases and anneal it and try it again. If it has sufficient bullet tension now, then your problem is that the cases have been fired and resized so many times that they have become work-hardened and are springing-back after they come out of the sizing die.
However, if you have only been handloading a month and the dies are new, I suspect they are out of spec.
Sometimes you get what you pay for, sometimes you only pay more for what you get.
Three shots are not a "group"...they are a "few".
If the Bible is the literal, infallible, unerring word of God...where are all those witches I am supposed to kill? (Exodus 22:18)