Tom,
I see you are from WI. The first thing that comes to mind is that with very low pressure and cold temps, you can get poor ignition and bloopers. I'm in Texas and have never experienced this but have read about it a number of times on this board. Second item would be patterning the load to see what is best in your gun. Third would be how dirty the powder is. But 6200psi is a great number. My go to 12ga load is 6400psi by the book.

Hopefully some of the northern folks will be by shortly and give you some powder/load info that they have found works in cold weather.

Hope this helps.
Ithaca1

Last edited by ithaca1; 04/09/15 05:47 PM.
Bill Johnson