I have had two 300RUM's. Neither one of them liked the Scirrocos. 3" groups. It is very common for alot of 300RUM's not to like the scirroco. This gun loves matchkings and 200gr Partitions. Here is handloaded Partitions on Sat. at 100 yards. I know handloaded data don't help you but as I recall I took some factory 200gr on a moose hunt a few years ago. They shot 1.1" groups.