I also found that the BW seems to have started in early 2011 with distributing old G3 with small telescopic sights to the troops in Afghanistan.
But I am not certain if that is due to the temperature issue: it maybe is due to the fact that the G3 uses 7.62 mm callibre. Maybe the combat distances in Afghanistan were found to be longer than what the 5.56 callibre can negotiate with some minimum precision.
Also, the discussion on whether the loss in penetration power against thin walls and wooden objects when they went from 7.62 to 5.56 is worth to save money, is very old, but still being run. To go to 5.56 mm was a politically motivated, no military decision over here. Firing a huge cloud of small callibre in close-distance infights maybe is better, but at longer distances and against covered targets I - by amateur's instinct - would prefer the heavier callibre automatically, even at the price of lower firing rate.
The alternative would have been to introduce the G27 (HK 417) which uses 7.62 mm, instead of the G36. But that model now is only used as a sniper rifle in the BW, I think.