All the tools tested except for the Metabo have a chuck with a slip collar that releases the bit when you slide it back. Loading the bit with this type of collar is easy. Simply push it in and rotate until it you feel it click in and engage. All four of these chucks look slightly different, but they operate the same way.
Metabo, on the other hand, uses a twist chuck. This requires the operator to twist the chuck to load and release the bit. It's not quite as easy as the slip-collar chuck, but it's not a deal breaker, either.
The dust seal at the end of the chucks is an important feature, sealing in the grease while sealing out abrasive masonry dust. Rubber dust seals that stop spinning when contacting a hard surface will end up lasting longer. The Bosch, DeWalt, and Makita seal ends stop spinning readily with a light touch; the Hitachi takes a lot more friction to stop. The Metabo doesn't free-spin, but the end is capped with smooth metal so it should hold up as long as the rest.
Hitachi's rotary hammer got the job done faster than the others, but the trade-off was more vibration and noise.
Credit: Photo: David Sharpe
We liked that the chuck on the Metabo can be easily removed and replaced with an optional accessory drill chuck for more versatile drilling and driving applications. The bottom half twists and instantly releases the entire chuck from the tool's drive end.
Bosch and DeWalt have a clever depth-gauge design. On most rotary hammers, the depth gauge is set by tightening the side handle, which locks itself into place, as well. These two models have a depth gauge-locking configuration that is independent of the handle-cinching mechanism. A spring-loaded button clamps down on the depth gauge, engaging teeth that provide a slip-proof lock that is easy to adjust.
We also liked the cast-aluminum housing on the front of the Metabo. Since this is the business end, we like to see a heavy-duty material carrying the brunt of the punishment. New, durable plastics work well enough, but I prefer the toughness of metal. Bosch's housing has added durability with rubber patches on the plastic housing in known wear areas.