My custom Kirby/Lilja 300 RUM with massive 30" Lilja #8 contour and NF 3.5-15x56 driving the .508 BC 155gr SCENAR made quick work of 717 yard buck. Problem is the artillery piece is too heavy for me to shoot off hand. Being the former silhouette champ, and deadly accurate offhand with my 6.5 lbs a-bolt 270 WSM - I planned on carrying the little a-bolt in my hands for deer I jumped then using the artillery for when I was set up at long range. The Kirby gun with Harris bi-pod worked better than I expected at long range, but I jumped several GINORMOUS bucks at close range - and because I couldn't carry the big RUM on my back, I had to leave the little a-bolt in the truck. My plan for next year is to take one of my old stocks (replaced by custom stocks), fill it with lead (to make it RUM weight + 4lbs ) and use it in my pre-hunt training. Whats the best sling or other mechanism to carry a heavy gun.