I am new to the P320 and have only shot 150 rds so far. I usually field strip and clean my guns at 200-250 rds. Should the chassis also be removed and cleaned at the same time or can it go for longer periods before it is removed and cleaned? If longer, when should it be cleaned and what parts should be lubed?

Interesting question. Since most guns cannot have the "chassis" removed to be cleaned, I would think it would not be necessary.

Just make sure the TDL is installed before you put the slide back on.

I take my slide off and remove the FCU every time I fire mine to clean it; but only because it's my carry gun and I want to ensure it's clean prior to loading it back up.

Every few hundred rounds, or when convenient, I remove the slide, barrel, recoil spring/rod, and FCU. I give the slide and barrel a good wipe-down with Hoppe's #9, and swab the barrel with #9 as well. I use an aerosol gun cleaner on the FCU (not carb cleaner or brake-clean), and then use TW 25 aerosol to lubricate the FCU. I use TW 25 "tube" grease on the slide rails, and put a light coating on the OD of the barrel and on the upper part of the hood. I spray the recoil spring and guide rod assembly with TW 25 as well.

May be overkill, but keeps it running well for me. And, I now have about 1500 rounds on the Gray Guns trigger, it is really smooth.