Okay, well I'm going to post what I hope will be a final resolution to this issue and the rabbit hole goes even deeper. On Friday December 11th, having tried several fixes but none successful as far as solving the HST ammo jam issue, I called Taurus customer service, had about a 10 minute conversation with a very knowledgeable rep who listened, repeated the issue back to me that I was having, gave me a ticket number and asked me to send the handgun back to them. This is my only gripe about the whole process, is that I had to pay $50.00 to ship it two day Fed-Ex to them, but in the end it was worth it. So, I got it shipped out at around noon on Friday the 11th, it was accepted first thing Monday morning the 14th. Thursday the 17th I got a notice that it had been inspected, repaired, and was being prepared to ship back to me via Fed-Ex.........but with no information on what they had done. I was a bit skeptical, actually I was very skeptical, I didn't get the email until after they closed on Wednesday so I called them first thing Thursday morning and asked for the same rep who was, to my amazement, actually available. She looked up my ticket number, confirmed what I had stated about the barrel and the ammo FTF issue, and stated they had replaced, get this, replaced the slide catch, replaced the slide catch spring, and made an adjustment to the slide............no mention of the barrel whatsoever. I verified with the rep that the barrel checked out ok, politely ended the conversation then just sulked at the fact that once again, customer service is a thing of the past and that I could fully expect my Taurus G3C to jam just as it had before i sent it back to them. So, again surprisingly, Fed Ex delivered my pistol back this last Saturday morning around 10am, quick shipping from Bainbridge, GA. I got the handgun out of the box, noticed it had definitely been fired, I cleaned it before I sent it to them, so definitely had been test fired. I'm no gunsmith, that's for damn sure, but I didn't notice anything different in the internals, just that it needed cleaned, which I did. After getting it all broken down, cleaned, oiled, and put back together, I put 15 rounds of HST 147 grain in one of my 15 round extended mags, locked the slide back, hit the slide release, got ready to laugh snarkily and...........the first HST round cycled perfectly......as did the 2nd, the 3rd, all the way up to and including the last round. I quickly loaded a 12 round magazine from a different box of HST rounds........all 12 cycled perfectly and without issue. I then loaded up 6 magazines, 2 15-round ones and 4 12-round mags with a vast assortment of Federal HST, American Eagle FMJ, Winchester Silver Tips, Hornady, Remington Golden Sabre, and Speer. All of it was 147 grain....6 mags, no malfunctions at all. I did this obsessively over the next couple of hours, trying to make something jam but I could not. so, much to my surprised, they fixed it.....now my question to the many more gunsmith savvy members here is....HOW WAS THE PROBLEM NOT BARREL RELATED???????? I mean, they HAD to have done something to the barrel, didn't they? If I put the G3C barrel into the G2C, I no longer have the issue with HST rounds jamming in the G2C which I did before I sent the handgun off for repair. Possibly they didn't notate something they did to the barrel? Am I taking crazy pills here?...lol. Don't get me wrong, I'm thrilled the issue is fixed but I had really done a lot of testing to arrive at the conclusion it was something barrel related. The slide catch and catch spring never even entered into my mind......anyway, just wanted to post some closure to this topic, this one will keep me shaking my head for a while. Going to take it to the range this weekend and sacrifice some hollow points to make sure it actually works ok, but it's cycling just fine now. Thanks for all the tips and info everyone posted, I really appreciate it. Kudos to Taurus warranty repair, with the exception of high shipping cost of the weapon, they were top notch all the way from start to finish.