I am using a MecGar Officers colt 1911 6 round magazine with the colt spring but a Kahr follower and it's been working fine, and is very flush fit with the gun. It does not always lock the slide back when empty, but I can live with that given how flush the base is to the grip. Had to remove a little material on the front of the bottom for the magazine to go all the way in.

Today i am shooting with the stock 6 round magazine with 7 rounds inserted. How?
I used the maggut spring from my Shield maggust +1 kit and a colt stamped steel metal .45 follower with the original Kahr base plate and retainer.
7 rounds fit and the magazine has been function fine so far. Will have to do more extensive testing, but this looks very promising. I have even contact Magguts asking them to develop this as a new product.