7 mag reloading conundrum?
I was testing 7 rem Mag loads today and had something weird happen. I was testing 140 gr Berger vlds and working my loads up. I started with the all loads .010 off the lands so oal to ogive was 2.650", all loads are using h1000. First load was 67 gr and velocities were 2715, 2732, 2743. Load 5 69.8 gr velocities 2930, 2930, 2956 and no pressure signs. Load 6 70.5 velocities 2982, 2969, 2969 no pressure signs. So everything is looking good. Test load 7 at 71.2 velocities at 2048, 2020, 2048 what the heck is happening? Test 8 to see it's 72 gr and velocities are 2290 and 2271 I didn't shoot the third because I wanted to make sure I loaded these correctly. Got home pulled the bullet and sure enough 72 grains. So what happened? The only thing I can think of is these 140 gr bullets have such a small bearing surface (.265) that when I seat them to .010 off the lands there isn't much in the neck to allow the pressure to develop properly, maybe 40% of the bearing surface is in the neck, is this logical at all? The 150 swift I measured had a bearing surface of .515 and easily allowed for long seating depth with plenty on bullet being seated. Also I use a redding neck bushing and size all brass so there is .002 (.282 ID) neck tension. Any help on understanding what happened would be appreciated. I'm thinking of going to 160 AB or 168 bergers because I'm thinking this must be a bearing surface issue. Thank you for any help in helping me learn something
Last edited by pyroducksx3; 07-10-2011 at 08:03 PM.