Kahr sells an extended bolt handle on their site; not sure if it's in stock or not. Someone on the boards mentioned leaving the bolt locked back for a week or so, i did that and it *seemed* lighter, but it could've just been my imagination.
In any case, i made my own quick-detach bolt extender out of a 1/2" hex bolt cut down, with a neodynium magnet epoxied on the end. I mention quick detach since it's only held on by a magnet, and the bolt handle reciprocates, i suspect it'll fly off while shooting. I stick it in the bolt handle when i'm charging or locking the bolt back. Works fine so far.
Take a basic 1/2" partially threaded hex bolt from the hardware store and cut it right at the threads. This is important because there tends to be a slight chamfer from the threads to the solid part of the bolt. The chamfer will help the extender sit better in your bolt handle. Then cut it again to the length you'd like to make it useable. Mine is eyeballed to be like 3 finger width.
Once it's cut, smooth out the rough edges. Optionally, get a small neodynium magnet (rare earth magnets that are very strong for their size), and counter-sink the right sized hole in the tip. Epoxy the magnet in there and let it cure. When it's cured, you can go ahead and use the extended bolt handle. DO NOT SHOOT WITH IT IN PLACE.
Nice job finding a solution