Did some K-22's come with 4" barrels? If so, that might answer your question.
Yes. They were known as the K-22 Combat Masterpiece. The revolver at the bottom of this photo is a K-22 Combat Masterpiece, the one at the top is a standard postwar K-22 Masterpiece with a 6" barrel. Notice the shorter gun has a Baughman front sight while the longer gun has the standard Patridge front sight. But the box the OP is asking about clearly says 6" barrel on it.
Did you try just laying it in there straight. That's usually how they came.
That's not how my Model 17-3 came in 1975. It will only fit in the box as you see here. And the box is 12 1/2" long.
The same thing with my Model 19-3 from 1975. With its oversized target grips it will only fit in the 12 1/2" long box the way you see it here.
However............
if you look at my boxes you can see they are from the Bangor Punta era. They say so right on the box between Smith & Wesson and Springfield Mass. These boxes were marked A Bangor Punta Company. Bangor Punta boxes such as mine were made from 1966 until 1985. the OP's box is from before the Bangor Punta era. You can see the difference if you compare the photos. That style of box was made from 1957 until 1966. These boxes were simply known as the Blue Two Piece Boxes.
I cannot explain why the OP's box is 1/2" shorter, perhaps that is just the way they were making them then.
An interesting question to ask is when was the OP's K-22 made. If he does not know, I can probably tell him if he posts the Serial Number. In the interest of science, I just grabbed my Model 17-3 from 1975, a K-22 Masterpiece from 1953, and a K-22 from 1935. They all have to be placed in my 12 1/2" long Model 17 box on an angle just as you see in these photos. None of them will fit any other way. Measuring the bottom of the box, where the revolvers actually sit, it is 12 1/4" long by 4 1/4" tall by 1 1/2" deep.
