Fail to Extract is USUALLY a problem with the tension on the extractor.Just got if for X-mas! Fired it once, and it's on its way back to Kimber for them to look at it.
The lost round in the magazine won't feed... ever.
And occasionally the shell won't extract.
I'm so bummed out!
Fail to load last round...usually a spring issue with the magazine.
I have an UC II - .45 ACP. I had several issue you describe.
1 - Replaced inner and outer springs with Wolf (8.00 or so)
2 - Ditched the Mags...they tended to gouge the alum frame. The springs in the Kimber Mags = not good. Replaced with Wilson Combat
3 - Adjusted the tension on the extractor...sounds like either too much or too little... I'm banking on too little.
Once I tuned the UC... it has been flawless. I change the springs every 1000 rounds or every year...whichever comes first ...as it is a carry weapon, and do not want a malfunction of any sort.
I do not push a lot of rounds through this one...it is for protection, not plinking. I keep it tuned and in top condition. with a little maintenance, the Uc's are an awesome weapon.