Originally posted by chibae My primary concern is the weight of the lens hanging down while walking. If I have a free hand I can reach down and support the lens. But, too many times I stop and put up my bins leaving the camera and lens hanging supported only by the camera strap. Which in turn leaves the lens supported solely by the camera's lens mount.
As others have said, this is not an issue. The 55-300 is one of the lightest telephotos available for Pentax. The slight addition of the 1.4x TC has no bearing either. I routinely hike with the DA*60-250 (a much heavier lens) with no issues. I might have a concern with the DFA*70-200 or DFA150-450 but even there not much of a concern. The lens mount is designed for this and has been doing it for a very, very long time with no problems.
The only time I have seen any word of a mount issue was when the camera / lens was actually dropped. And even those have been remarkably few.