In this part of the US, temperatures during hunting season can often be well below freezing. A lot of people will bring their guns indoors after they spend the day outdoors. The warmth will then cause condensation to form on the inside of the gun; on the rails, in the firing pin channel, etc. Normally this isn't an issue but I remember during one deer hunt where the temperature very rapidly dropped below freezing and guns stopped running. Firing pins would not fall, semi-auto actions would not work after the first shot and pumps would lock up. Of course you don't get to find out any of this till you have a herd of deer running past you. Then the "click" is usually very loud.The only shotguns that would run that day were the pumps as you could put the butt on the ground and force the slide down.
I have used a Remington 870 more than any other pump and I really like the gun. I can take it apart with my eyes closed and I can always get it to run no matter what the conditions. However, lately, I have been thinking a lot about Keltec's KSG. The handiness of the short weapon and the huge magazine capacity make it especially desireable. As a home defense weapon or a deer gun, I think it would perform admirably. However, while I have played with one I have yet to shoot it. I will be thinking seriously about purchasing one when they hit the market this fall.
On our recent visit to TN, Oleg made some ads featuring my daughter and the KSG. You can see how short and handy it is.

Photo by Oleg. Click the photo in the link to see the full size image

Photo by Oleg. Click the photo in the link to see the full size image
Before anyone starts going on about the "Indian context", here is my disclaimer.
Disclaimer: Please note that the above post is based on my experiences in the US and might not be relevant to the shotgunner in India