velocity issues

[snipecatcher]

Originally Posted by elmr007

Shooting 240gr mk. OAL 2.260 H110 powder 10gr.
First shot is 1147, second 1109, third 1083, fourth 1060 and then it stays there for the rest of the string. Hence vertical patterns. Doesn't matter what primers I use. Have tried benchrest,magnum ,standard ,Winchester ,cci, federal. All the above. Also tried 220mk and 200mk ammo, same thing.

Are you cleaning your barrel in between shot strings? All of my barrels do that to some extent when they have been cleaned.