Production Class 308

JHS   "I would be interested in your opinions about using tumble lube in below freezing weather. I am not getting any leading but the first shot of each string, after letting the barrel cool 5 minutes or so, seems to be inch away from the ultimate center of the group."   I used to shoot in cold weather much of the time and found the same thing; 1st shot after barrel and fouling cooled/hardened would be out of the group.   After having tried everything including dry brushing I found that just shooting a fouler into the sighter target before starting the new group was the best solution. I use reject bullets for such “foulers".   This last week I tested some loads in my own “Production Class” rifle; a M70 varmint .308W.  However, since I modified the barrel by turning it down for the front sight base the rifle would actually be in “Heavy Rifle” class now.  I decided, based on the last year+ worth of testing and experience with the .308W and 30x60 XCB cartridges using the 30 XCB bullet to step outside of the “what has always been done in CBA matches” and use what has proven very successful for cast bullet accuracy.   The bullets were cast of #2 alloy, WQ'd, culled for any defect and weight sorted.  Instead of using a heavier bullet I used a lighter weight bullet.  Instead of shooting the bullets slower I shot them faster.  Instead of using the faster burning powders I used slower burning powders. I tested 5 different powder charges each of 2 different powders with 10 shot test strings and met with very good success.  With one powder I got 3 groups right at moa (100 yards).  With the other powder I got 2 groups under moa.    No intent at criticism of what CBA match shooters are doing.  I'm just providing information on what is working for me.   Here is the rifle;