Originally posted by BigMackCam Honestly, the whole worry with plastic mounts is, so far as my own experience goes, unfounded. The DAL 55-300 weighs nothing compared to many lenses... It will have zero impact on the plastic mount. You could fit plastic mounts to considerably heavier lenses and not have any problems. Wear and tear from constantly fitting and removing the lens is more likely to be an issue, but my DA35/2.4 shows no signs of that either...
I agree; reports of broken PENTAX plastic mounts are quite rare. However, I have been hanging out on the FujiX-Forum for the past year and I've read reports of broken FUJI plastic mounts - maybe 4, 5 or 6 cases reported in a year. Fuji uses a plastic mount on two of their kit zooms, the XC 16-50mm f/3.5-5.6 - and the XC 50-230mm F4.5-6.7 (and maybe others). As I recall, most of the broken mount reports I saw were about the longer lens.
I have both of the above zooms; the reason I bought them was to save weight when traveling by foot. I also have Fuji's mid-range XF 18-55mm F2.8-4 zoom (metal mount). The image image quality of Fuji's plastic-mount lenses is actually equal to their more expensive zooms, which is saying a lot.
I've never worried about the mount on my Pentax DA 35, but don't assume all plastic mounts are as trouble free as the ones Pentax makes.