When you say "double feed" is the round in the chamber live or an empty from the shot that jammed?
If its an empty from the previous shot, odds are you got an extractor or ejector problem.
Since the mags worked in the Kimber, odds are it is not a magazine issue.
Spent casing in the chamber and a jam from the top of the mag.
I think that the mags are fine. The Kimber gets shot a lot and all of the mags work fine in it. Even the new SA mags that came with the loaded are gtg with it.
I think it's the extractor too. I heard somewhere that the claw on the SA extractors are a little different than most and can be an issue. I don't know if it's true or not.
Like I said, I'll put a few more rnds through it just to make sure that it's out of the break in period. I hate playing 20 questions with customer service so I like being able to say that it's out of the break in period, 5 brands of ammo were used and several different mags were tried. It cuts out the BS.
When I first got the gun it wouldn't cycle. I would load the first rnd by hand, pull the trigger and the slide would not cycle far enough to the rear to extract and eject the spent case. It also wouldn't move far enough to the rear to strip a fresh rnd off of the magazine. The next trigger squeeze would result in a click instead of a bang. I'd rack the slide by hand and this would be repeated.
Believe it or not I put 2 boxes of ammo through it like this before returning it. It kind of sucked but it probably helped my trigger squeeze. Bang, click, rack, bang, click, rack, etc.
I'll probably get to the range tomorrow for an hour or two. I'd like to get it sent out and back before the next match. I am kind of disappointed in SA though. I stayed away from their M1911's for years because I got a POS from them in the late 1990's. Here I am again wondering if this gun will be unreliable after several trips to the factory.
I guess the lesson is to do my research. I had researched and was looking for an STI Spartan. I couldn't find one in my area so I took a chance on the Loaded based on Springfield's rep. Live and learn.