Thanks for pic, interesting to say the least, but the results are what counts. If I can get my hands on some of these, have to give it a try. With the head down that far in the case definitely takes up air space, and with the light charge wouldn't be too concerned about a pressure problem. Apparently you have shot quite a few with no problems. Also, bullet jump from cyl. to bbl no real negative problem either according to your groups. What about wind effect, any experience along this line when testing?
I have seen some vintage H&G molds on the E-Bay sight in past. Those were prob some of the best boolit molds made my opinion.