Got my CM 40 a few weeks back. Went to the range and shot 110 rounds. 100 Independence FMJ, 5 Buffalo Bore and 5 Liberty. Broke 2 followers. Received 2 followers from Kahr. Next visit to the range while rotating 4 mags, 2 followers broken in 100 rounds. Contacted Kahr again they said they would send a RMA if I liked. I told them no just send the followers.
I work in machine shop and have been around precision mechanical assemblies for 35 years so surely this smells like an interference problem.
Locking the slide back and putting a small strip of paper down the feed ramp I put in an empty mag. I could not remove the paper shim without resistance. Ah Ha !! Feed ramp is slamming the follower after last round ( the only time the follower is exposed ). This may not be for everyone but a stoned the bottom of the feed ramp with a Dremel, then some 600 paper then polished only that spot where I ground with a felt wheel and some jewelers rouge. Took Prussian blue and applied to the feed ramp and put in a empty mag. Still had a little interference so I repeated the process until no Prussian blue transferred onto the follower. Put 100 rounds through today without a hiccup using the same mag all the way and NO BROKEN FOLLOWER. Problem goes away.
Now I'll add some Talon grips and my summer EDC is ready !!!!