Here is another point. The new 6-1/2" length for the .357 starts showing up about 18xxx. That leaves about another 24,000 guns to be produced to the end of production for the .357 flattop. If Ruger was just using up the last of their stock then started using BKH-34 printed boxes, that would leave a big chunk (probably close to half of those 24,000) in 4-5/8" boxes.
Would Ruger really have had 12,000 boxes of any model in stock ready to use?
I'm thinking Ruger really didn't care what the box ends said on them, obviously not because the 6-7/8" Mark I continued to have a non-catalog number "TARGET PISTOL" box right to the beginning of red hinged boxes in 1972/1973.
2nd, there are only two BKH-46 printed boxes known. Yet non catalog number boxes for the 6-1/2" .44 flattop go right to the end of .44 flattop production. Would Ruger really have had roughly 10,000 boxes on hand ready to use up for the 6-1/2" gun? How about the 7-1/2" and 10" .44 flattops? Would Ruger have ordered thousands upon thousands of those printed boxes to have on hand assuming they would sell that many guns? I really don't believe so. And if that were the case, what models did they use all those BKH-47, BKH-40 and BKH-30 printed boxes on? I can't see them going to the burn pile, and the few that I do know of that were used with other models have end labels for that model.
I think when they got close to needing another batch of boxes, they just hit the "reorder" button and the supplier printed whatever their last order was.
Chet15