Any ideas why my 1-8 twist 6.5mm barrel refuses to shoot 142\'s well Just got a new barrel in 260 remington caliber. It is 27" finished length heavy contour 1-8 twist. In the last month I have ran in excess of 500 rounds thru the barrel while doing some load development. The 120's work just fine but for some reason the 139, 140, & 142 grain bullets don't seem to shoot nearly as well. The pattern on the various brands of 140's is pretty consistent. Out of 10 shots in a group 5 or 6 will be in a nice tight 1/2 MOA group with the rest being randomly placed flyers which open things up to between 1 & 2 MOA. It seems to stay consistent at all ranges out to 600 yards. 100 yard groups show the flyers as do 600 yard groups. I have tried various powders, velocities, seating depth, and anything else I could think of to get the bullets to shoot well. I ran the shots across the chronograph to see if the loads might show a lot of velocity variation. No luck so far. Any suggestions? If I can get this problem licked the rifle will be my new 1000 yard prone match rifle.