I only trimmed the nose down to my preference and trimmed the lock-plate to fit the slightly stubbier interior of the CS45 mag. All of my modifications were to the magazine body. The P220 floorplate likely won't do for the narrower 9mm mag body. There might be better choices out there, the P220 was chosen only because I had an opportunity to buy four mags for the P220 cheap after looking at a friend's gun and learning of their low profile.

It would be pretty important to see how much room was left in a full CS9 mag, considering the extra capacity and small size it may have less room than the CS45 did and not offer up much of a reduction. I found that a stock fully loaded CS45 mag would allow 1/2" more compression of the top round. I basically took away 0.2" of that still allowing 0.3" of top round compression.