Shooting in cold weather brings an interesting set of challenges, especially if the weather is really extreme. Temperature affects you, the gun, and your ammunition. I was shooting clays in the States some years ago and it was a freezing February afternoon. I was well clothed, but very cold and feeling it. The cold was ‘deep’ and made you one stiff. I pulled a muscle in my back when swinging on a target and it took weeks to heal.
So, warm up (indoors) with a little gentle exercise before shooting – walking on the spot, shoulder rolling, gentle (and slow) arm and neck exercises. A hot drink will help too (alcohol will not). High tech clothing alone may not prove adequate to prevent problems. Wear layers in cold weather. They need only be thin, but are more effective than bulk alone. Use a singlet vest under a thermal one for sub zero conditions. Shirts should be warm and offer good movement. The British Army Norwegian Winter Warfare shirt is near ideal as an extra layer. You can wear long Johns (I usually don’t though because they may restrict movement). Good boots are important – I like Brasher Supalites or Dubarry with thick socks. You will choose your own jacket, but arm movement again is paramount, a thin quilt inner may be useful too.
Finally, hats and gloves. A lot of body heat is lost through your head, so wear a hat! I like trilby, but whatever you opt for, you’ll want something more than a cotton baseball cap. Gloves are essential. I wear quality, thin leather ones – and wear them year round. Don’t change gloves with the seasons – the right ones will fulfill all tasks. They are not just for keeping the hands warm, they also help in holding the gun – cold weather reduces grip purchase.
Clothing thickness will affect gun fit. If you end up looking like the Michelin Man (and you shouldn’t) you will need a significantly shorter stock, but even well conceived clothing may require ¼-1/2” less stock length in compensation. The easiest route here is to use interchangeable pads, or, you may opt for winter and summer stocks. Some shooters however just have spacers that they put in for the summer months and remove for the winter.
Don’t forget cold weather may also bring poor light (making focus tougher) or glare from the low sun. Both may be minimised with the right shooting glasses, so this must be taken into consideration.