1. 1911
2. In reality, that is an unanswerable question. Everyone has a different opinion based on different beliefs and criteria.
3. What is meant by "best" is undefined.
However:
The most expensive production handguns are currently made by Korth in Germany. They make less than 500 units per year.
The most popular handguns in the world are made by Beretta, Glock and Sig Sauer.
The handguns most given out as prizes by US Special Forces and Green Berets for winning internal contests are usually Colt 1911 45 ACP variations, Colts being the most valued and 45 ACP being considered the most desirable caliber.
The police in the USA mostly use caliber .40 SW.
Police in most other countries use the 9 mm Luger cartridge (9X21 mm).
The most collectible older handguns were made by Colts Manufacturing Company, although that is debatable. But if price is an indicator, older Colts realize the highest prices
For self defense what police and federal agencies choose is probably the overall "best".
So we see that "Best" is rather hard to define.
As for historical best handgun, it does depend on the time it was made.
When the 10 shot savage .380 and .32ACP pistols came out they were held in high esteem by those used 6 shot single action revolvers.
As for all time favorites, some say the Colts 1911, some say the Browning High Power, some choose variations of the Sig Sauer or Glock.
Also little known, the broom handle Mauser caliber .30 has amazing handling and pointing characteristics.
In its time (1860s -1870s), the Colt Navy .36 ball revolver was a sensation.
Of derringers, High Standard .22 magnum comes to mind.
It goes on and on....
One minor correction, 9mm Luger is 9x19mm. 9x21 is 9IMI
Contenders include the M1911, Nagant, P-38, GP-35
The first auto-loading handgun ever made was the Laumann pistol.
The P9R is made in Hungary by the FEGARMY Arms factory
See link.
Could be a rifle, shotgun or handgun.
No sn provided.
Impossible to answer without a detailed description of all markings
It depends on where you are. In the U.S. only a few states require registration and there is no federal registration.
50-126
100-400 USD
Hawaii has manufactured goods such as steel and other minerals these are made from the large amounts of the mine stuff they have there in Hawaii They usually have the best manufacturing companies ever in the United States
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Glock