Pulse control. Eh Gads!
Wearing a shooting jacket is the easiest and best way to reduce the pulse down the sling.
Having a great cardiovascular system is very important. Shooting is an athletic sport, working on the tread mill, jogging, will do it. Gary Anderson,
http://www.odcmp.com/comm/Director.htm, ex head of the CMP, he was into jogging and other physical activities when he was winning National Championships.
Don’t shoot in hot weather. My pulse rate spikes and everyone else does in hot weather. Groups are much tighter in cool weather. Cold weather, group size goes up again, but it must be due to the discomfort and dry eyes. Plus the fact you can’t feel your trigger finger. I will wrap my hands around the barrel after rapid fire, let the warmth of the barrel defrost my digits.
In cool weather you can “calm” yourself down. I have seen it., I have done it. You sort of calm relax, think about slowing your pulse, and for a second, you see the front sight stop moving. That is when you pull the trigger. Does not last long, pico second or so. I calm relax when having my blood pressure and pulse checked. It is cheating but it works.