M-38 or 91/30 Mosin Nagant. They're extremely rugged and will function in spite of being dirty, frozen, wet, and whatever else Alaska and I can do to them. I suspect either would function with part of an old sausage biscuit down the bore, though I'm not going to try it.
I ususally keep the bolt with me, at least in areas where a break-in is potential. What's a thief going to do with a Mosin-nagant and no bolt? Order a new one from Tapco and headspace it, then rob the bank with it?
I see several problems with handguns kept in the truck, at least in these parts. First and foremost, they aren't powerful or accurate enough to deal with wildlife "issues" that may arise. The exception would be a nice hunting handgun with a scope, but there's no way I'd leave anything that $$ in the car. Second, they can be swiped too easily. IMHO a handgun is best when kept on the person. Third, since most bad guys are going to have short guns, a long gun gives you an enormous advantage should your life be in peril. If deadly force isn't quite called for, an old battle rifle makes an excellent hand-to-hand weapon. The biggest problem is making sure you don't hit too hard. Those steel butplates were designed to smash heads like melons.