Beretta 686 problem

[rainydays]

My beretta 686 20 Ga. will not fire the second barrel when the temperature drops below freezing. I suspect that it is a lubrication problem, as it shoots fine when the temps. are warm.
Just wondering if you knowledgeable folks would agree with this analysis or if you might link it to some other problem. Also how would I go about fixing the problem. Haven't ever had one of these apart. Any ideas would be greatly appreciated.--tr