Worked some process of elimination yesterday and it's the mag. Ran down to Ammo Depot and picked up a WC. Now the WC and one of the two Kimber mags work fine. I'll try to figure out how to fix the bad Kimber mag. Looks to me like it has the same problem my Tikka CTR mag had - the spring was bent so the follower tips the round way too far tip-up.

The only reason to keep a defective mag is to have one or two that are known to fail to use to practice malfunction drills. If kept for that purpose, mark it very clearly with a yellow paint marker as a warning and do not mix it up with any other mags that can be used for carry. Otherwise, smash it with a hammer so no one will try to use it and toss it in the trash. Seriously.

On "good" mags that are used for EDC, replacing the mag spring once a year is easily done for routine maintenance, but that is a different issue than starting off defective.

If this is a EDC pistol, buy all Wilson's since you know they work. Quality mags that are 100% reliable are way less costly than losing your life.

For additional consideration
Like a known issue w staccato
1911s do not like to have mags slammed in as it can overtravel and cause mag damage no cause this issue

I'm an engineer and like the challenge of fixing stuff. I'm not the brightest but I like to learn.

That said this will be EDC for my FIL and I'll probably just take the mag back to the place we bought it and see if they'll take it back as defective. I've been buying stuff there for 15 years and I'd even just trade it even for a WC to replace it if they'd go that route since they're about the same price. Long story short...I agree with you.

I have yet to know of a Kimber that was issue free. Won’t own & won’t sell them.