Update on my Mossberg 100ATR
Thanks for all your comments everyone.
I have only had one opportunity to shoot this rifle again. I took my oldest son (just turned 11) out this summer to the bush and we set up some targets in front of an existing backstop. It was really a chance for him to shoot our .22 rifle, but I managed to try some Federal Premium 130g rounds.
Due to the terrain I could only shoot to about 75yds. I had a card table and sandbags which worked well but wasn't nearly as stable as a proper shooting bench. My result was somewhat predictable - I shot a few 3-shot groups and each was no better than those of my initial review here. However, the spread was mostly horizontal while the elevation of each group was around moa (3/4" difference). I assume that this spread was basically shooter error.
I also managed to go looking for mule deer for a few days at the beginning of October. I drove to some areas and usually got out and hiked into some still-hunting spots. I only saw does (no doe tag) and therefor did not get a chance to shoot the rifle in the field. I can at least say that I found the rifle easy to carry. Being a big guy (6'-4", 240 lbs) the rifle felt very light to me. I doubt that I'll ever want to consider a "light mountain rifle" as a necessity.
On the negative side, my feelings regarding the blind mag haven't changed. I can really see the advantage of being able just pop in or out a mag instead of having to load in or cycle out cartridges every time you get in or out of a vehicle. Although I don't consider myself a "road hunter", sometimes exploring new terrain leads to multiple short drives in a day.
The cheap scope is still on for now. I promise to install at least a 3200 Elite or Nikon Prostaff in the future. For now, though, the cost of dental braces for two boys is 'biting' into my wallet hard!
PS - when I bought some ammo at a local shop (Hunter's Sporting Goods in Surrey) I noticed they had a 100ATR for sale. I didn't manage to see the price though.
Regards to all.