I had an experience yesterday that made me rethink the possible cause. It is not unusual for me to find a slight variation when I seat bullets in my .270 and 6.5mm Creedmoor. I loaded 10 rounds each in the Creedmoor with 40.0gr of H4350, and seated 140gr ELD-M, 147gr ELD-M and 140gr Hornady SSTs. As an example, the SSTs were seated to an OAL, base-to-ogive, of 2.255” for a 0.02” jump to the lands. When I primed the cases I stood each one up and they did not rock or sway. But I had 4 of the 10 seat 2.257 to 2.259 inches which, in the past, I figured was a slight change in the position of the ogive during bullet manufacture, and I would just adjust and reseat to the desired OAL. The same thing happened with the other two 10-round sets.
When I stood the 4 up on the table, they rocked and swayed, indicating the primers were no longer flat. Instead of reseating them, I gently “re-primed” by pressing the primers back in. That solved the problem. They measured 2.255”.
That brought me to consider that just maybe, since the cases are not 100% full with powder, there’s enough air in those cases that seating the bullet pushes the primers back out a bit. These are cases that may have been fired 15 or more times and maybe the primer pockets are not as tight as others that don’t deliver the same problem.
What do you think?
When I stood the 4 up on the table, they rocked and swayed, indicating the primers were no longer flat. Instead of reseating them, I gently “re-primed” by pressing the primers back in. That solved the problem. They measured 2.255”.
That brought me to consider that just maybe, since the cases are not 100% full with powder, there’s enough air in those cases that seating the bullet pushes the primers back out a bit. These are cases that may have been fired 15 or more times and maybe the primer pockets are not as tight as others that don’t deliver the same problem.
What do you think?