I've used this a lot with my AR10 (308) and Rem700 (300 Win Mag). The Sled can handle the 308 all day long, easy to see where the bullet landed because you're still spot on target with hardly any movement. 300 Win Mag is a totally different story. The sled will inch back slowly after every shot and doesn't provide enough stability to consistently see the impact. Even with 125lbs of steel shot loaded on this beast, it still moves around.
Adjust-ability of the sled is pretty awesome. Only thing I can dock it for is the left right adjustment knob has too much slop in it before any adjustment is made. One of the bolts came lose and fell out after extensive 300WM shooting one day. Assembly instructions are pretty poor.
Pros: Rock solid, magazine space, adjust-ability, weight
Cons: weight, poor assembly instructions, doesn't sit still for magnum loads
This review was written in the old system and had content requirements that are different than reviews written today.