My P40 and P9 are similarly configured with ported barrels and O-rings with the flat metal bases. Kahr did sell black ones for a while... pricey at first, then dropped the plain black ones, but could use a black touchup pen by Birchwood Casey... does wear off, though.

As I did with the P40, I put an O-ring on the magazine with the metal base plate to stop pinching. The 3/32" thick by 3/4" inner diameter neoprene O-ring fits and doesn't cause binding or loosening of the lockup of the magazine.

15/16" to 3/32" by 3/4" on the label. The bottom mag has a 1/8" thick O-ring... too fat and prevents secure latching of the magazine.
I just wish they had some metal bases for the .45's.
Wynn
USAF Retired '88, NRA Life Member. Wife USAF Retired '96
Avatar: Wynn re-enlists his wife Desiree, circa 1988 Loring AFB, ME. 42nd BMW, Heavy (SAC) B-52G's
Frédéric Bastiat’s essay, The Law: http://mises.org/books/thelaw.pdf
Thomas Jefferson said
“A government big enough to give you everything you want, is strong enough to take everything you have.”
and
"Peace is that brief glorious moment in history when everybody stands around reloading".