That photo is scary!
Truly glad you and both firearms made it out of the war zone ok.
I've been doing this reloading thing going on 40 years and, like most others have already stated, I rezero the scale (beam or electronic, it doesn't matter) before each and every session. You've learned a valuable and free lesson. Well not entirely free I guess since you have to throw away several cases.
Jim - I think I have your check weight!
I also use a .224 bullet that, oddly enough, also weighs 49.90 grains. (I checked it on a Mettler lab scale). I don't recall which brand it is, but it's a "50 gr." SP and is either Speer or Sierra