I have been breaking in a 65-284. with sierra 142smk- The Load after first 20 rounds went to 51grn.of 4831sc...Velocities around 2830 to 60...Then 51.2 grn.went to 2880 +or-..then 51.5 =2930 one spiked at 2975 ,and in between...all good groups! Overall the 51 grn load shot best, but not by much...Groups were .306-.350- .450...No primer dimple ,or any sign of pressure throughout load tests.Temperature was 45 degrees here in MD. today.if this has any bearing. My Question is, should I concern myself with the speed? Is it that important,Or is it only important out at 1000 yds?