Yup. I've run into that before on the M992.
There used to be a conveyor system inside the body of the M992. The vehicle would back up to the M109 and extend the conveyor into the lower back hatch of the M109. Crews found the conveyor slower than transferring ammo by hand and started removing the conveyor. More recently that has become a system-wide standard, I believe. They even modified the M992's back doors so as to provide protection to the crew while transferring ammo.
I think the bustle that's been added to the M109 turret also complicated conveyor operation.
The K10 has its conveyor come out of its front. This allows the vehicle to drive straight up behind the K9 and "plug in". It's a simpler construct from the M992 and, IMHO, a more elegant solution.