Thesnufkin: Millions of partial trained conscripts?
That might make sense for most armies (though not Germany's) in WWI, but not the 19th century.
Look at Britain. Look at Prussia. Each has a completely different attitude and would probably make good use of a bulletproof vest if a practical, affordable one is available (and yes, the key word is affordable - armies are expensive enough as is) But to look at numbers in general...
Military and Naval Personnel of the Powers (1880/1890/1900)
Russia: 791,000/677,000/1,162,000
France: 543,000/542,000/715,000
Germany: 426,000/542,000/524,000
Britain: 367,000/420,000/624,000
Austria-Hungary: 246,000/346,000/385,000
Italy: 216,000/284,000/255,000
Japan: 71,000/84,000/234,000
United States: 34,000/39,000/96,000
Source: The Rise and Fall of the Great Powers, by Paul Kennedy.
The 1816-1880 military personal of the powers (which does not include Italy and Japan) is taken by Kennedy from another source, so comparing the two is difficult - but the numbers are still short of a million for any given country.