This isn't really a "Mod", but rather an alert to a couple of products of which I think everyone should be aware.
The photos below are what started out as a Blue/Black P-3AT.
I stripped the bluing from the slide and gave it a nice brush finish. I also left it in the white (Bare metal). I also stripped and polished the barrel, extractor, and recoil spring retainer. I re-blued the extractor and retainer, and blued the barrel. I have been carrying and handling this pistol almost daily for the past couple of months, with no problems with rust.
I also added some material to the back strap. I have fairly large hands, and one of my main problems with this pistol is that the trigger reach is really too close for me. My trigger finger would actually be stopped from fully pulling the trigger by the thumb of my shooting hand. I tried a couple of different products, but this one is the first that actually worked.
So....How have I been keeping the rust at bay? With Bullfrog Heavy Duty Rust Blocker.
This stuff is a lubricant and protectant that uses the same vapor inhibitor technology that is used in the packaging from many firearms factories today. That little wax paper looking bag that your new pistol probably came in is impregnated with the stuff. Just wipe your gun down with a little of this about every other week. Give it about 5 minutes to dry, and wipe off the excess. No more rust!
What about the grip extension? That's Fast Cap's My Grip.
This stuff is a heat activated moldable, rubber. When it is heated, it becomes moldable and sticky. Once it cools, it is no longer sticky, and does not snag or grab my covering garments. It will stick to just about any clean surface, but removes easily with no residue if or when you want to take it off. They tell you to boil it, but that didn't work out so well for me. I used a heat gun (I think a hair dryer would probably work just as well.) to mold the back strap that you see. It's been on there for a couple of months now. It only came off once when I wanted to see how hard it would be to remove it (It wasn't) and if it left any residue (It didn't.) All I did was heat-up the side that was attached to the gun just enough to become sticky again, and pressed it back into place. While it does have some give to it, it is a bit harder than your average rubber handgun grip.
Even with the High-ride grip safety that came on my PT-1911, I had trouble with my grip actually deactivating the safety. I put some of this stuff on the safety to make the "speed bump" extend a bit higher, and now have no problems. I carry this pistol quite a lot, and this stuff hasn't moved since I put it there a couple of months ago.
These items are cheap, and unlike a lot of things these days, actually do what the manufacturers say that they will do.
I hope that you guys find this useful.