In use with single camera strap mount, a speed strap and Kirk flash bracket.
8.6 pound Nikon 500mm f/4

Because the weight is transfered to the body thru the forearm even very heavy
lenses can be used freehand. 12 pound Sigma 300-800mm f/5.6

Kneeling. Sigma 300-800mm f/5.6

Prone. Sigma 300-800mm f/5.6

Carry with monopod attached with Kirk security strap.
Sigma 300-800mm f/5.6

Mounted on a monopod and with red dot sight. Sigma 300-800mm f/5.6

Mounted to tripod with gimbal head. Sigma 300-800mm f/5.6 w/ Red Dot Sight

The Camera Mount System: components, selection, and setup

Quickdraw. Nikon 500mm f/4

From kneeling to standing with monopod.
Nikon 500mm f/4

From handheld to tripod and back to handheld.
Sigma 300-800mm f/5.6