Gents, thoughts please. Made up some test loads for the 243 with 100gn Hornady BTSP starting at 38.5 and going up to 42gn (max load) test shot last night. The lower loads were appalling 4" for three rounds at best. Only when I got to 41gn did I start getting down 1 and bit inches. Got dark before I tried the max load. Even the 41gn was still shooting 3" lower than factory RWS 100gn which has a box velocity of 3000fps. The Heym shoots RWS very well and three rounds touching is the norm.
My thinking is that with the lower loads they were not giving anything like the velocity to get good consistent spin on the bullet, nor enough pressure to get a good clean burn. Once it's getting up to 3000 fps there is enough rotational spin to keep 100 gn bullets stabilised.
Real question is even at the high loads will there be enough spin to keep the bullet stable down range, or does spin slow down as velocity falls off down range.
I'm looking at the 100gn bullet as its the legal minimum in Scotland for the bigger deer and I want one load to do everything. I want something that's good for 200yds, but most shots at 100 or so.
My default is the RWS ammo, but at £35 a box of 20 it's getting expensive. I suppose I could go 85 gn for roe/foxes and keep 100gn RWS for hinds.