NOPE. The M-67 does not have an airspace. It tumbles because the center of gravity is to the rear as a result of it's flat based design. I have sectioned numerous M-67 and M-67 types and none of them have an airspace like the 7n6. Some M-67 or M-67 types have a very small airspace in the tip, like the size of the head of a pin, but this is not intentional nor does it have any effect on it's performance, it is simply a manufacturing artifact.
I have also sectioned many other Russian and other 7.62x39mm projectiles, including the 8m3. I do not beleive that the 8m3 was designed to meet a specific goal of lethality or anything else. I think the scoring is simply a result of manufacturing technique. I have other examples of various internal jacket configurations that suggest manufacturing intent, not performance.
1DD