I shot my first rounds of hand loads this weekend for my 300 Rum. I loaded the following:
Nosler brass (first 5 new brass, others 1x fired)
215 M primers
Imr 8133 (88.5 to 91 grains)
Berger 230
Neck size only
The 89.5 and 91 loads had primer cratering bad. All shots had ejector marks and slight crater. I'm thinking my headspace is too tight that could cause this? My brass is pretty tight when chambering. All my factory ammo shows ejector marks also. I was hoping to get more velocity since I have 29" barrel.
On separate note, which do you think I should start next steps of load development? Also, if I full length size could I get more velocity and lower pressure?
Thanks,
DoubleG