Very few instructions enumerate all the variables that determine this initial velocity. Barry Pickup in his PDF file names them all although he does not provide them in a clean list and all he says about selecting some combination from them is “The fewer variables you allow into your delivery technique, the easier this muscle and memory training will be and the more accurate your bowls will be.”
This article contains one sentence that is actually at odds with my own observations. Pickup says, “Since the position of your arm as you assume your stance on the mat has an effect on the amount of back-swing you use and thus the degree of arc in your overall delivery swing, this is a good place to start your adjustments for varying weight and the distance your bowl travels.” My own bowls teacher has a very gradual, very measured backswing that is quite unrelated to the position of her arm as she takes up her stance on the mat. I have adopted this. Where I start my pendulum motion is fixed and completely unrelated to how large or small my backswing is. Nevertheless, Pickup’s is the most complete presentation I have found and the most useful to me.
The elements that contribute to the distance a bowl will travel are:
back swing elevation
degree of crouch
length of your stride
release of the bowl above the grass
rotation applied by fingers if any
arm bending at the elbow
added muscular acceleration from the arm
wrist bending at release if any
I have tried to list these in the approximate frequency with which I have observed them. Most deliveries are some combination of the eight elements.