Made my first 300 MK loads yesterday, got some nice groups but also some flyers every now and then. I thought it was bad shooting because it was getting dark but today the thing was still there,in a good light. I used only one load today. I have a stock Sako TRG-S. Shot a bunch of 250 Scenar moly factory rounds with less than half an inch groups and never noticed this drift. So: With the MK:s the first shot from a cold barrel is there. Right where it´s supposed to be,yesterday and today. Vertically the same as Scenars. The temp is arond 30F now so I let the barrel cool down for only five minutes between the shots. What happened was that the POI drifted to the left again, just like last night but now it actually stayed there,I got the best groups at more than an inch to the left. This is only 100 yds shooting here, testing. After a few rounds it started to drift back to center, got 1/2" groups again but closer to the "starting" POI,verticalwise. ??????? Is this just bad shooting or what? Any experience appreciated,I used a decent bench, maybe the rear support could be better. I also had the bipod attached but folded to "carry" position for some real world weight. Here you can see what is going on. The first one is there,then the 1/2+ inch group is somewhere else. After some groups it moves back towards the center and yesterday I got two 3/8" groups as well -but in a wrong place. I have shot only moly 250 factory Scenars before and this is something new. The load was only 2595fps because of the 26" barrel but it is fine for my hunting purposes. 85 grains of VV N165,standard COL, CCI 250 Magnum primers. SD for ten rounds was 16. Any ideas? I´d be quite happy with this for 500 yds moose with 1/2" grouping but the drift is no good. The scope is fine,Scenars shoot where they are supposed to. Plus,the twist is 10", not 12". Is it just the heat? If so,why does it drift back?