Ron,

You don't suppose that the plastic sabots contracted or shrunk somewhat due to the extreme cold? It stands to reason that it could very well be the cause. Softer materials expand and contract more significantly due to temperature extremes. Try measuring the base of one of your sabots at room temperature (with a good quality micrometer or vernier caliper) and write down your reading. Then put it in the freezer overnight. Take it out the next day, wipe off any frost with a dry towel and DON'T handle it with your bare hands any more than you have to...and check it again. The extreme cold temps you were shooting under may have caused the sabots to shrink enough to where they seemed loose or easier loading than they normally would.

BPS