Q:  What is the best way to clean the P7?

A:  There are wide and varied responses to this question, but the procedure that follows is a good answer.

The P7 Cleaning Ritual

Ah, nothing like the cleaning recommendations for the P7 pistol to bring out the debate team on the best methods.  Opinions are widely varied but the following is a good synopsis on how to treat your P7 right.

Courtesy of "Sawbones" from the Park Cities Tactical Board

Standard cleaning consists of:
MP-7 gel in the barrel, with moderate bronze bore-brush scrubbing. Let it sit.
MP-7 spray on the insides of slide & mag well; scrub inner surface of slide with toothbrush, patch wrapped around small "bottle brush" to clean inside of mag well.
Breech face and barrel feed ramp brushed with stainless steel "toothbrush".
Gas piston chamber cleaned with reamer, then with H&K-supplied brush for the purpose.
Gas piston cleaned with MP-7 & bronze "toothbrush", then with 3M-brand green polymer kitchen scrubber. (This gets most of the baked-on crud off.)
Wipe off all MP-7, run patches down bore 'till clean (with repeated scrubbing of the bore as necessary).
Oil-soaked patch run through bore, followed by a clean patch, light oiling of outside of barrel and of slide rails, then reassembly. I do not put any oil on the gas piston or in the gas piston chamber, even though H&K says to "lightly oil" these.

Moderately-thorough cleaning:
Includes the above, plus removing the firing pin assembly, disassembling it, and cleaning the parts, as well as cleaning the firing pin-assembly recess inside the slide, and the firing pin hole, also cleaning the gas piston chamber with solvent-soaked cotton swabs (held by forceps), and detailed cleaning of the gas piston flanges, using a tool I made for the purpose, consisting of a large-bore IV needle (16 gauge) which has been cut & flattened to produce a very small scraper. (I know, I know, H&K says "do not use hard tools to clean the gas piston...", but you can do anything if you're careful, and I've been doin' this now for 15 years.)

Really-thorough cleaning:
Includes items in moderately-thorough cleaning, plus removal of the grip shells and spraying the entire mechanism down with Gun Scrubber, 'till no more dark gunk comes out, then letting the gun dry, very lightly lubricating the moving parts of the squeeze cocking mechanism, then reassembly.

Really-thorough cleaning once a year, moderately thorough cleaning two or three times a year, standard cleaning whenever the gun is fired, unless I'm going to shoot within the next day or two again, in which case I'd clean only the barrel.
Nothing's too good for my babies!
(Besides, it's sort of a meditative experience.) The standard cleaning used to take me two hours, now it takes a few minutes, 'cause I'm not as "picky" about it as I used to be, plus MP-7 really does help, since it makes much less scrubbing necessary. I wish it had been available years ago.