How many shots can a handgun make to say it's over used ?

I don't know how many thousands of rounds have been through my Sig 228?
Only thing ever replaced on it were the grips, and then only because I wanted rubber grips with finger grooves,

My own personal Glock 17, which I have owned since 1989, and before that was a range gun when it was new from 1987-1989, has seen the better side of 200,000 rounds (I bought it from the range, they were selling it cheap, lol). I still carry this pistol as my primary defensive arm. I can still shoot bullseyes with it as easily as breathing.

So I guess it depends on the gun. Most quality firearms, the answer is, "More than you can put through it in a lifetime."

Unless of course you are a competitive shooter, in which case you would not be asking this, you'd be too busy putting yet another case of ammo downrange for practice.

Beyond normal inspection during cleaning, a rule of thumb for typical handgun should be serviced (springs replaced, gunsmith inspected, etc) every 5000 rounds. There is no reason a handgun that is taken care of should not last until at least 25,000 or even 50,000 rounds.

Manual, I have several handguns that I use for competitive shooting events, over the past 42 to 43 years the only handgun barrels that I've ever had issues with were military issue 1911 barrels and instead of bore wear it was mainly link wear or wear from the barrel bushing.
I have a Browning BDM, FN model Forty Nine, FNX, and Sig P226C that all have over 10,000 rounds through them and they still shoot competition groups with the bores. My biggest thing is to keep up with the springs and wear points more than the barrels.
I'll agree with Gwolf on one thing, the quality of the metal used makes a big difference. I have a Browning Buckmark 22 that I retired after less than 7500 rounds. I have a Walther GSP E that has over 35,000 rounds through it that I shoot benchrest with and it still shoots like it's NIB.

If you take the time to shoot medium controlled ammo, clean and lube the firearm well, and do preventative maintenance on it then I would say you'll never see the limit on a quality handgun.

Question is a little vague (English is not your 1st language?). I've heard stories of a Glock shooting 3 million rounds: http://dailycaller.com/2013/08/19/10-advantages-of-the-glock/

My G19 is still going strong 5500+ rds.
But my lorcin on the other hand clapped out at about 2500 rds. Lmao

I would say the care of a gun would make it look overused more than round count. Also the quality
of the firearm would enter in the picture.

That depends on the quality of the barrel, whether it is properly maintained, and what kinds of ammo that is used.

A high quality barrel that has been properly maintained and typically not using a hot load (+P) can last over 5,000 shots easily although parts such as a recoil spring or barrel bushing in semi-autos will need to be replaced before that and a revolver will need to be re-tuned and the force cone replaced.

I'd say north of 50,000

It all depends on the gun.

When you drop $700 for a Walther PPK or PPK/s you would probably expect it to last 12,000 to 15,000 rounds - roughly 60-90 years. When you pay $350 for a copy - this would be a gun using lesser metals, lesser alloys, and not machined as well - you can expect the lifespan and number of operating rounds to easily be cut in half, if not 40% of the original model. Say you are a Security Guard in a city - and your company requires you to buy your own pistol and qualifying annual is your only range time... maybe you fire the thing 1 box a year? Here buying a Taurus copy of the Model 92 would be smart money. On the flip side - you are also firing 2-3 boxes a month doing action pistol events...... here the nicer made pistol that will last longer for $450 makes sense.

In centerfire rifles - after 2500 rounds a match barrel is considered to have degraded to standard grade. And after 14,000 rounds a barrel is said to be 'washed out'. I have never seen a pistol with a washed out barrel - although I have seen pistol that have been fired so many times they are loose as a goose and you wander if the next round is when it will finally going to explode in your hand.....

Probably over 25,000, change the recoil spring every 5k or so and as long as the barrel has good rifling it should be fine.

couple million

I don't exactly get the question.

Most hold twelve rounds, although some hold twenty to twenty-five.