The "British"- meaning the British government- did not make an 8mm Mauser rifle. Some private gun makers in England have- but without more information, there is no way to answer. Please repost your question with some identifying information, and we can try to help. Let's start with all markings on your rifle.
Numerous commercial and custom makers have made 8mm Mauser rifles in the last 100 years
Brazil used a number of Mauser rifles over the years. Most were in 7mm Mauser (7x57), but later versions were .30-06. That number you have is not a model number. sales@countrygunsmith.net
I don't and haven't seen one in a lot of years.
They made those from 1890 to the early 1900's
only paid 89.00 for mine about 8 years ago,just ok shape.they go for 190.00 to 280.00 at the gun shows
The Turks have made firearms under license from various makers for over 80 years. Mauser, H&K, Mosin Nagant, etc..
First there was repeating rifles, like the Lee Enfield and the Mauser. A breakthrough would be the Maxim Machine Gun. Airplanes were not used yet. Instead they used Airships and blimps to bomb cities, at the German's did in WW1. The navies used pre-dreadnought and dreadnought battleships as well as destroyers and battlecruisers.
During which era? Germany manufactured several types of guns throughout the years, whether it's the Dreyse Needle Gun, Luger pistol, Mauser rifle, MP38 and MP40 submachineguns, MG34 and MG42 machine guns, Heckler & Koch firearms, etc.
Most German wartime pistols and rifles were manufactured in 'blocks" of around 10,000. They would then proceed to the next letter. There could be two blocks of the same letter made in different years. You should have a manufacturer's code on the pistol like AC (Walther) or BYF (Mauser) and the year made after it. Such as BYF43. Look for these codes to get your info and go from there.
The Date is located on the slide of the pistol. Look for a code such as "AC41" or "BYF40". The alpha characters are the manufacturer's codes, and the two-digit numbers are the years (i.e. 41=1941). I think AC is Walther and BYF is Mauser.
WikiAnswers provides a brief (wiki) answer. The answer YOU have asked for would fill a good sized book and would include a LOT of opinion and subjective judgement. Guns made for military use are often (but not always) very durable. Candidates for the "most durable" would likely include the British SMLE rifle, the Mauser K98, the US 1903 Springfield, and the Russian 91/30 Moisin/ Nagant. The proof would be the number of these guns that are still shooting at nearly 100 years of age.
I don't know for sure, but here are some suggestions and starting points to look at with your own research. All of the people I'm about to name had popular mass-produced semi-auto pistols. As you know there is often a big difference between when a certain kind of thing is "invented" and when it becomes popular and available for the public to buy.Hugo Borchardt had a semi-automatic pistol in the early 1890s.This gun was the inspiration for the famous Luger pistol, invented by Georg Luger in the early 1900s.Paul and Wilhelm Mauser produced a semi-automatic (and fully automatic too) military pistol called the C96 Mauser or "broom-handle" Mauser back in the middle 1890s.John Moses Browning designed a number of semi-auto handguns, both small and large, in the late 1890s through the WWI years. The famous Army model 1911 pistol is what he was most famous for, but an earlier version of this kind of gun, in a smaller caliber, came on the market in 1903, and it was very successful. Browning designed a lot of guns for the Colt company.