hobby rocket using rocket candy

Today I tested a homemade rocket engine made with r-candy and clay catlitter (for the nozzle and plug).
The nozzle was made from clay catlitter with a tapered hole I used about twenty grams of r-candy then l put a thin plug of catlitter. I had placed the rocket upside down on a bamboo rod clamped to a table with a scale under the engine but when I ignited it the sound was so great that I had to step back and could not get a reading but from the looks and sound of it the small 500 gram scale would be maxed out then at the end of the 3-5 second burn the thin plug at the end popped off shooting the engine up in the air this was becouse the core was not drilled all the way to the end so when the burn was near an end it found it easier to escape threw  the thin plug then the narrow nozzle.