So lets get down to business... shall we?
Offside roundhouse is gonna be easier than the onside roundhouse, especially for those who feel more confident with their strength than balance. To get the general idea what this move looks like watch the video...
It is easier to get enough speed while doing offside moves because you can do a stroke as you descend from the top of the wave and increase your speed. As far as the angle is considered check Onside Roundhouise Article
Again the most important thing is that the move has to be performed dynamically... Unlike cartwheeling (continuous strength application) blunting requires strength impulse... To be able to deliver such a forceful snappy movement in a C1 you need a lot of balance so if you fail while trying blunts do more carving/clean carving and then try again...
Onset phase. Notice that the boat still carves aggressively to the onside while all the weight and dynamics of the body is thrown to the offside.
Complex weight transition+hand pivot+paddle movement. Onside rail aggressively disengaged (this creates enough rotation dynamics) offside rail almost off the water.