Try some of the neoprene diving gloves, not eBay shite but the real deal. They cost from a fiver (if on offer) upwards.
Provided your hands are warm from the off they retain heat and they are fairly dexterous. I wouldn't like to say nimble enough for loading but I don't shoot a catty so have never tried.
They are made to offer a natural relaxed hand position. Ideal for clenching something ie a catty, rather than an open palm fit like most gloves.
Worth a look.