Hi guys, first post here and I'm hoping you may be able to help me out a little. I'm in the process of having a 243 AI built and I'm trying to gather some information for loads to try. I'm hoping to shoot either Berger 105's or 115's and I'm curious as to what powders are getting the best results since I've seen multitudes of load data posted on different sites. I've got Hodgdon 4350, 4831 and Retumbo sitting around now. If anyone has suggestions on a starting point with any of these or any other powder for that matter I'm all ears. Thanks!
I have had excellent luck on several .243 AI with Retumbo and the 105's. I am shooting 51 grains retumbo in my current rifle. With Fed 215's, 105 Berger, and Lapua brass I am getting right at 3270 out of a 27" Broughton. Get a drop tube though because it is a full case!! You can shoot 50.5 as well. As for a fireform load 49 grains of retumbo works really well. I have also shot 52 grains of Magnum (formally Big Boy) and it seems to shoot very well. I am just not sure how temp stable it is though. My current rifle with this combination regularly prints in the low 2's and holds pretty close to .5 MOA to 1K. Good luck!
I shoot N-165 with the 105 A-max's. Was wanting to shoot the Berger 95's but had to slow'em down to group per Walt and they did. I wanted a fast 6mm so I tried the 105's they shoot faster and group just as well. This is in a 1-9 twist 27" Pac-Nor. I shoot RL-19 in my 1-10 with the 68's match.
I shot a .367" three shot group at 300 yds about a half hour ago. 105 A-max and 44.5 grns. of H-4350 with a CCI-250 mag primer. This is a follow-up group after shooting a .555" three shot group about a week ago. 8 twist benchmark barrel.