The Redding Shell holder set are taller than a standard shell holder to minimize sizing.
A standard shell holder is .125 the Redding Competition shell holders are in order .127, .129, .131, .133, and .135 tall. Most chambers are larger than standard dies and so with the Redding Competition shell holds you can customize your sizing by choosing the right one. Occasionally
you had a chamber smaller than the die such as the OP has. The solution is to shorten the distance between the shell holder and the shoulder of the die. The easy way to do this is to take the top of the shell holder off by the amount needed. In other words creating a reverse of the Redding Competition shell holders.
As has been mentioned before the simple way is to check with a feeler gauge and once the proper sizing is achieved take the thickness of the feeler gauge off the top of the shell holder.
You could also try other die and shell holder combinations in hopes of finding as set that works without any modifications.