It seems that for much of history, the firearms available to civilians were equivalent or even higher-technology than those used by standing armies. Some examples would be rifled barrels in the Revolutionary War period, repeating rifles in the Civil War period, and semi-automatic rifles in the WW1 period. The major standing armies seem to have been slow to adopt this new technology in favor of the “tried-and-true” options of the time.

When did this change?