Geo tracker, you bring up a lot of interesting points. I don't know where this idea came from that flat base cast bullets could only be driven at such slow speeds.
I used to do silhouette shooting, to 200 metres, with 44 magnum revlovers. I have owned and shot extensively, five different 44 magnum revolvers, two S&W and three Ruger Super Blackhawks. I bought the well known Lyman 429421 mold and the similar bullet gas check mold. After trying each bullet design in my revolvers, I came to the conclusion that using gas checks was a waste of time. The plain base shot every bit as well as did the gas checks. Further, there was no difference in causing leading of the barrels. And I loaded them up. My load was either 22 grains of 2400, or 24 or 25 grains of 296/H110.
I also had a Marlin 44 magnum rifle. I tried the same loads in the rifle, to see if i could see any difference in accuracy, between the gas check version and the plain base. With the iron sights on the rifle I could detect no difference in accuracy. And remember, in the rifle the bullets would be travelling in the order of 1750 to 1800 fps!
Later, I got another Marlin 44 magnum and on this one I put a scope. I still could not detect any difference in accuracy between flat base or gas check bullets.
I think the biggest reason that some loads lead the barrel, is mainly because of how smooth is the barrel. Of my five revolvers, one didn't lead the barrel at all. Another, of the same make, leaded up the barrel, no matter what kind of cast bullet was used. The other three came somewhere in between. Neither of my Marlin rifles leads the barrel. The time I just run a cleaning patch through them and they come out shining.
I have always been an experimenter. I always wanted to try things out for myself, to see what the result sould be. By the same token, I pay little, or no attention to the myriad of unproven theories that are so common on the CGN.
I too, have been caught in the past. When tumbling cartridge cases became popular, It was stated, and seemed to be common knowledge, that it was dangerous to tumble loaded rounds. So I didn't do it and I even told people not to do it!
Now, it is well proven that there is no danger involved in tumbling loaded rounds.
Live and learn.
