I have a Model 12 Precision Varminter in .223 with a Leupold 6 1/2 x 20 scope. My problem with this gun is that it shoots a different impact point depending on the ambient temperature. I have tried different powders, different brass, different primers and different bullets in all combinations. The load I settled on when I got the gun was 25 grains of AA2250, 55 grain Hornady V-Max moly, Winchester Brass and Federal Match primers. This load shoots excellent groups for me at 150 yds. when shot in nearly constant temps. With a cold barrel at 70 degrees it shoots on center. The next day at 40 degrees with a cold barrel it will shoot one shot somewhere within an inch or more. I live in Iowa and in the early spring or in winter we can indeed get temperature variances like that from day-to-day. I sent the gun to Savage and they had no problem with it but they shot it in their indoor range over two days with no temperature changes. They don't know or won't talk about what could be causing my problem. Do any of have any ideas as to what could be happening to this gun when the temperature changes?

Thanks.