It's not just you Tedd. Circulation decreases as we get older. I have the same problem if my hands get cold.
If you are keeping your core warm and wearing warm gloves while sitting, but still having trouble flexing your fingers, then you are not getting enough blood to your hands, or you are getting arthritis.
For sitting around, a warm glove with the fingertips cut off works good and a warm mitten can be worn over it
For hiking, when you don't need as much insulation, glueing leather onto a tight fitting glove works great. Its not for target sessions, but fine for one or two shots at a time.
Still, flexibility and muscle tone= circulation, if you have 10min a day to spare for some hand exercises.