rimfire_crazed
Master
I was in a hurry with my original post and the "brass of unknown age and origin" issue really stuck out to me as a problem (and it still is), but yes, the other missteps that were taken were equally problematic.
That being said, it appears the the OP has corrected his problem and is well on the way to finding a safe and accurate load in his rifle.
OP - be careful seating that far out. If chamber pressures are already high, they could spike further during that short jump to the lands. Many shooters shoot with their bullets making a very short jump, or even with the bullet seated against the lands, but their powder charges are adjusted for what could possibly be an increase in start pressure.
That being said, it appears the the OP has corrected his problem and is well on the way to finding a safe and accurate load in his rifle.
OP - be careful seating that far out. If chamber pressures are already high, they could spike further during that short jump to the lands. Many shooters shoot with their bullets making a very short jump, or even with the bullet seated against the lands, but their powder charges are adjusted for what could possibly be an increase in start pressure.