As mentioned the primers may need a little more pressure when
being seated to stop the misfires?

You might check to see if your weapon is going all the way into Battery.
The case needs to rest on the chamber ring and if the bullet is
just a little too long it might be pushing the case back, causing problems.

Yes the 4.3grs of powder looks like it is falling off in fps.
You need more case space or a different powder to help out.

Keep on trucking........

PS;
are those pictures 640x480 ?
I usually get that and then enlarge.