I think if it were mine, and I already got 600 rds through it without a problem, then it started feed jamming, I'd check the magazine out first.
You didn't say if you tried other mags or not, if you didn't, try that first.
The comment on "locked wrist"....there is something that some call "limp risting"...holding the gun real loose will cause the spent shells to possibly fly in another direction, and has on occasion been blamed for reliability problems. It makes some sense. The slide needs to travel back at a certain speed, and if your hands and arms are moving back with the gun while holding it real loose. it does seem possible you could be interfering with the operation of the pistol. Someone else on this site could explain that much better than I can. That being said, I have practiced shooting from lots of different positions and also with one hand, and I'd expect if I had a slightly different grip sometimes while rolling in the dirt and coming up shooting, the gun...I hope, would still work.
So maybe, some guns are more picky about keeping a firm grip and locking the gun into place (which I do most of the time anyway).
And maybe, guns can be less finicky by playing with the recoil spring pounds...ect...but then again, there are people on this site that have a much more in depth knowledge of these details.
If other mags are still giving you feed jams, then it might be time to send your gun to springfield, it should be free if you just got it. If they don't satisfy you, then it might be time to see a smith, but I'd let Springfield attempt the job first. ($$)
I have a mil-spec, so far no problems, but just ordered a Ed Brown Extractor and slide stop anyway, I have enough rounds through it now where I know I got a good one, and I'm going to be replacing some parts a few at a time, just to get some higher quality in the gun. But so far, I have no complaints on the SA Mil-spec, for the money, I got a good tight pistol I can do anything I want with.
Good luck on that feed jam...and let us know what you find out later, I more I read on here the smarter I get.
Jimster