Don't know if this one's the BEST "col[d] weather survival rifle," but... I was just wanting a reliable, hack-around "camp carbine," as in deer camp or just camping generally.
A while back I had a little work done on one of those Gibb's eletro-nickel plated .303 Brit "eXtreme carbines" so as to taylor it a bit to my specs. Mine's a No.4 MkI Long Branch (1944). While it shot fine, it still needed a little work. The muzzle brake came loose (bad roll pin), so my local 'smith put a new one in and added some soldering to make the whole front-sight unit (which includes the brake) stay put. On these rifles the front site rides atop the brake, so if the brake comes shootin' off, ... well, you won't be happy. He also smoothed up the trigger.
Gibb's "sporterized" Enfield stocks sucked for my 6'3 frame, so from Boyd's I ordered a relatively inexpensive foreend (which he shortened in length and bedded to the receiver) and a buttstock that gives me a sufficient length of pull, to which he then fitted a Kick-Ease recoil pad. The wood was sanded down, stained, and then sealed with a polyurethane coating to keep out moisture. Total length of the carbine is now 38 3/4inches; barrel is 19 1/2 inches.
The 10-round mag that came with it simply wasn't reliable, so after looking at gun shows, Springfield Sporters, etc., I finally came across a near mint No4 Mk I Lee-Enfield mag that works in THIS rifle.
The result: Well, the lower-ranged peep sight is DEAD-ON at 100 yds. Most factory or surplus stuff is in the black; some go two inches high at 100yds, which by my judgment is about a 200 yd zero. Groups are unusually tight for such a short barrelled, iron-sighted rifle. I'm sure this is due to the bedding and the smoothed-out trigger.
It's a tight little .303 Brit, and after shooting it a while it seems to prefer two loads: in FMJ it likes the Sellier & Bellot and in "hunting loads" it shoots very tight groups with the PMC 180g SPBT (these use Sierra GameKing bullets).
This is a reliable, accurate little rifle that I can take just about anywhere, rain or snow, and not have to worry about it or baby it.