Wool blocking the wind is a density of weave issue. While I sell Asbell wool, I wear wool from literally every where. I have different weights and densities.
Fortunately, all wool improves it's density over time. Unfortunately, it's actually an action of slight shrinkage. Yep....get your wool wet enough times, and it will be dense as heck. This is called "fulling" Thats why it is important to dry your wool properly...laying it out and blocking it as it it dries.
I find Filson to have an extremely dense and windproof wool right from the start. My Filson Mackinaw gets the nod when I am going to just wear one coat, and a bowhunters mobility isn't required. It's great gun hunting or checking coyote traps. But I can't shoot a bow with it. I wear a ton of Filson wool, but other than their sweaters and vests,it is not bowhunting gear.
Asbell wool is designed to be layered. It's roomy enough for a jacket, a windblocker vest, and maybe an extra Asbell wool vest. I also always wear my thick Filson sweater. I wore this arrangement this morning. 18 degrees, blowing snow, and I was never cold. I sat 3 1/1 hours and could have lasted another 2. Asbell pullovers and zippered jackets are also specifically designed for the bow hunter. Seems like an easy claim, but hear me out.
There are lots of Mackinaw "like" jackets out there. Filson make the best one, IMHO. But these are designs that originated with timber cruisers and gun hunters. Lots of pockets, usually extra wool around the shoulders, etc. Frankly, I think it's the best looking jacket out there. I have worn mine from funerals to traplines. But with all that bulk and extra wool, pockets and buttons, come problems for the bowhunter.
Teresa started her business with the pullover. It was designed to keep a bowhunter warm, concealed, and without the geegaws on it that cost extra $$ and snag bowstrings. Teresa and Fred sold nothing but pullovers until last year, when they added zippers. Seems like a simple thing? Nope. Teresa agonized about zippers....not wanting to increase cost, and not wanting to cause bulk and string catching pulls to the front of the jacket. And it isn't as simple as splitting open a pullover and adding a zipper. The pattern changed. Subtle as it seems, it took quite a bit to get the zipper "bowhunter approved". The shape of the body and the "flow" of the arms are different than other jackets....they are designed to accomodate the hunting archer. Thankfully, Teresa is married to a bowhunter who knows what works.
Other wool that is obviously designed for the bowhunter is 2 Tracks and the Grey Wolf products. Great stuff. I will be ordering a 2 Tracks for my personal use soon.