I have hunted NFLD quite a few times. Looking for quality rain gear is a great idea. I have spent entire weeks there where it never quit raining the whole time. If you are anywhere near a Cabelas , GM or Bass Pro Shop, or any other outdoor clothing store for that matter, I would go and try some outfits on and see which you think will be the quietest.
You tend to do a great deal of walking in NFLD and noisy rain gear will get you busted. I use Gore Tex pants and parka but still get wet at times. If it's not all that cold, you usually just tough it out but it still can get kinda miserable. I would not select the rain gear by looking at a catalog or website.
Not sure what month you are going in but temperature swings can be pretty good also.
I bought rain gear but never used it. I instead opted to just wear my waterproof jacket with removable liner and water proof pants. Jacket has a hood.
I stayed dry and comfortable in some miserable all day hunts.
My outer clothes dried out what little they needed overnight. Also take waterproof gloves.
Your 308 will do the job.
Hunted there in 2008 and got hit with bad weather. Cabelas dry-plus performed flawlessly. Lots of great stuff out there but like kudu58 said there is some noisey materials. Stay away from those. Your .308 will work fine on moose. Good huntin'
I hunted there also in 2005. You will want good rain gear but another thing to consider is good boots. The area I hunted, the ground was soggy. Wherever you stepped, an 18 inch puddle would form around your boot in most places. You will want a knee high type boot. Avoid leather and get a rubber/synthetic type boot. I wore Lacrosse Alpha Burly uninsulated with wool socks. We hunted the first week of October.
Leather will get heavy as it gets wet. There are several brands of knee high type boots out there, Muck boots and others. You will probably walk a lot so you want lighter gear. It is a different world up there, take a good camera!
I used an '06. The .308 will be fine just use a heavier grain bullet. Actually the guides we had liked when hunters showed up with non magnum rifles. They told us they see too many guys coming up there with magnums and they couldn't shoot and flinched a lot. They said when a hunter showed with a 30.06, 270, 308, etc... They knew the hunter would probably shoot better.
I'd look hard for the military surplus gortex stuff. I've been there three times and mine help up well. Much cheaper than a lot of the name brand stuff. Plenty quiet. Last trip one of the guys bought a off brand rain suit from Dicks or Dunhams, sounded like a herd of buffalo moving through any kind of brush.