I loaded 25 once fired rounds for my .243 I did 5 different powder charges and shot groups at 200 yds. I know most use 100 yds for load development but in the past I have seen loads Settelment in (go to sleep) over 150+ and produce better groups. The 4 horizontal holes is actually a 5 shot group. So my question is what causes a horizontal group? A high sd would produce a vertical string but what if anything may cause horizontal?