I'm very glad you posted this sir. I used a dremel last weekend to polish my feed ramp and the lip on the lower part of the G3C, no difference at all as far as failure to feed malfunctions. Like you said, about 1 in 3 or maybe 1 in 5 jam when you try to chamber the 147 grain HST round. I then loaded several 12 round magazines with a mixture of Winchester 147 grain white box JHP, Remington 147 grain JHP and the HST, about four rounds of each scattered throughout the magazine. The HST jammed on about half of its rounds, the other kinds of JHP chambered flawlessly. I have not been able to replicate the error in my G3 or G2C at all, both handguns feed the HST JHP rounds without issue, it's just the G3C. I see the same thing you are seeing, it very much seems like there is more movement of the barrel/feed ramp where it meets the lower part of the handgun. There's a gap where the two parts meet and that small diameter nose cone on the HST combined with the very pronounced serrations on the nose cone are digging into that gap. When it jams, it jams to the point I have to pull the slide back then drop the mag to clear it. I've also noticed that the 147grain HST round is just a bit longer than the Winchester and Remington rounds, so I'm wondering if that might make a difference also. I don't have any 124grain HST to compare the height of the two rounds. At this point, I'm not sure what else to do other than just load up the G3C with the Winchester or Remington JHP for concealed carry. The G3C shoots great, it's accurate as all get out, conceals very well, and is overall a great buy, but I'm just going to make sure I keep the mags for the G3C separate from all my other handguns so as not to use HST in it. I may take it to a professional gunsmith eventually and get an opinion on if there is anything that can be done. I know Taurus would most likely not be sympathetic to me opening up a repair request because it won't chamber a certain type of round....lol