Dave - good report, and of course, good shooting.
I don't see any problem with using them for hunting, just make sure to carry a wooden mallet with you. );>)
I have already read SL's report with his U Mag and it sounds like the entire "problem" revolves around having a very precise fit between the bore and the harder bullet material. Unlike pure lead, brass (or whatever) doesn't like to conform to another size without considerable persuasion.
When you consider the vast amount of differences even between .50 cal barrels, it seems to me that some sort of "cushion" material - at least on the rear portion of the bullet might be required to mass produce these bullets for the general public. Sort of a built-in sabot, but not a separate piece of material.