Just my first H&K  a USP 45. I have been shooting 1911s mostly.
The gun shoots great and so far is 100% reliable. I tend to throw a few low and left when I speed up.
The other shots are right on target. Are there any major do and don'ts that will apply with this pistol?
Shooting tips or hand position ( thumb above or below saftey when shooting )
Mantince and cleaning. How long will the recoil spring last?  Thanks for the help.

Rapidfire underwater is good for them...

Low and left usually means you are anticipating the shot (low) and are pushing on the trigger (left). Make sure every shot you take is percise - Practice pulling the trigger as slow as possible, letting the shot break and suprise you. Concentrate on the front sight and keeping it steady.

I've owned 5 USP 45's now, and they all run great. Can't think of any "don'ts" other than not shooting it. :)

I personally try to get my hand as high up on the frame of any pistol I shoot. I believe the closer your grip gets to the bore access, the more control you have over the recoil of the weapon. The grip I've been taught at many many training classes and that I've used successfully is this one :



I also shoot with my right thumb on top of the safety, that way taking the safety off becomes part of my draw stroke, and I don't accidentally activate it while I'm shooting. The USP has a decocker, but unless you're really cranking down on the safety at the time, you shouldn't accidentally activate it.

Maintenance and cleaning? "Sparingly" Is the name of the game. Make sure you lightly coat all metal-to-metal contact points. Other than that, the USP will run with very minimal lubrication, in fact it will run like a champ with none at all. My first USP 45 that went to Thunder Ranch with me 4 times and had logged over 12,000 rounds had 1 malfunction due to a badly sized reload on my part. I love these guns!

I am finally replacing the recoil spring on USP tactical after 5 years and close to 25,000 rounds. I wouldn't sweat it. You'll know when the spring is dying!

Doc

Hits going low and toward your weak-hand side indicates that you may be jerking your trigger instead of squeezing it.

Quoted: Either I'm having SERIOUS Deja Vu, or I've seen this post, virtually word-for-word, at least 3 times over the last few years. <queue the Twilight Zone music> -Troy

We know about you CA dudes.    

Your gun is great.  Practice and shoot.   If you have any issues, they should not be related to your firearm.  If they are, send it back to the manufacturer (HK)...

Also make sure you apply equal pressure with both hands on the gun.