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I have had eight or nine Kimbers, two of them Stainless Ultra Carry IIs, still own one. Never had anything like that.
But I have had some troubles with smaller semi auto pistols. These days I load all mags to full, let them sit on the shelf loaded.
Lock the slide open, let it sit on the shelf that way. After 2-4 weeks, take to the range and see how it works.
If it is still finicky, repeat. May take the springs a while to take a set.
Worked for several 9mm and .380s.

I know that does not help much if it is his only pistol, but since you have lent him one he should be okay.
Just out of curiosity, did you fire it and experience the same difficulties? It is a light, short barrelled .45, and if he's a first time shooter...may be operator error (limp wristing). Just sayin'...