Scott (snostorm) has inspired me to try to shoot my 300 hand held, plus I hate to walk around with my tripod. The image below is my homemade shoulder brace. It allows support on the top and against my shoulder in addition to my face on the hood loupe and my hand on the lens. Using my shoulder reduces the effect of of my breathing ans helps support the camera and lens. Now I just need to attach a across the body strap and I'm ready for the fog and rain to stop. I have tried it out my back window and it works but who wants to see images of tombstones in the rain. My red dot is still in the mail and will be added. I will post some images when the sun returns. The brace is made of 1/4" X 1" aluminum bar hand bent in a vise and over a roll with a tripod screw in a 1/4 -20 tapped hole then painted flat black. There is a twist at the shoulder and camera mount to allow for centering the Q to my face.
Hans