My 45 shield was a jamomatic out of the box and the slide stayed back after the last round about 20% of the time. I sent it back to the factory and they replaced the slide stop. The slide now stays back but FTF was far too common. The nose of the round would seemed to get stuck in the mag or feed ramp as others have described here. I hand polished the upper and lower feed ramps and things improved a lot. Still I often had to slap the bottom of the grip before the round would feed. Sent it back to the factory and it was returned with the chamber and feed ramp nicely polished. First box was Remington umc 230 gr. FMJ. The problem persisted. As I began to load some identical looking rounds from Fiocchi, I was planning to sell the gun and hope Taurus would come out with a G2c in 45. To my surprise the Fiocchi along with everything else I tried including lead SWC rounds worked perfectly. I measured the Remington's at 1.2585", a tad longer than everything else I had. It would be interesting to know if anyone has chrono'ed the Remington's to see if they are of a lower velocity. For now the shield seems one weak hand dirty reliable. Nothing else in its class interests me. I hope it will be as reliable as the Firestar 45 I once owned.
I polish all my ramps with Flitz. Works great, but didn't help this gun. Also, S&W polished ramps and chamber first time. Didn't help.
The shorter 1.200 cartridges definitely work better for me than the longer 1.250 ones, especially the Remington Golden Sabers.
I looked at a Springfield XDS 45 Mod 2 in the store and it felt really good. About the same size as the Shield, much better trigger, better front sight. The thing I like the best about it is you can get a much higher grip on it very close to the bottom of the slide which I think could be a big help. Wish I could find one to test fire.
In the meantime, I started having failures with the "new" slide that S&W returned with my gun the last time. Same FTF, next round still in mag, nosed down into the front wall of the mag.
So, I put the Hogue Handall back on, studied my grip and stance some more and made some changes. Went out and shot 3 mags 2-handed with no malfunctions, including one of my old mags with WWB FMJ which always had FTFs. I didn't try any one-handed because I wasn't in the mood for any disappointment.
I believe at least part of the problems could be me. Every new gun I've had has made me a better shooter in some way. Not quite ready to give up on this one yet, but it has been frustrating at times. It is a small, large caliber gun and may require better technique that what I've been used to, but I do have to make sure there's no mechanical issues.
I do think the magazines have something to do with it though, since when they are new and the springs are stiffer, the gun works great.
If I had never shot anything but Golden Sabers in this gun I would be very happy with it.