Standard procedure, when moving to a new lot of powder, is to re-tweak the load. Go to the old powder charge, on a short action,-.6 gr, -.4 gr, -.2 gr, even with the old load, +.2 gr, +.4 gr, +.6 gr. Stop when you see pressure.
And your incident is why, as well as making sure your rifle keeps shooting to its' potential.
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