Wm. Greener Sr. was talking about pin-fire breechloaders with paper shells, which were somewhat Rube-Goldbergish in their locking mechinism, notoriously leaked at the pin, and consequently were thought to shoot less efficiently than muzzleloaders, loads being equal. Also the paper shells often stuck, requiring the shooter to borrow a ramrod or cut a sapling to push it out of the chamber, while giving him pause to think that his "old reliable" muzzleloader wasn't so bad after all. And the part about being "unsafe," he meant shooting loose at the hinge-pin, which they did.
The Brits looked down on anything frog-like, so the London, Birmingham, and Scots makers were slow to take up on the new-fangled arm, which made its debut in England at the Crystal Palace in 1851. The pin-fire cartridge had been invented by Lefaucheux in about 1836, but it took years to refine it into a usable fowling piece.
Capt. Bogardus wrote in 1874 about his preceived need to use a little extra powder in his first late-1860s pin-fire breechloader. By 1871 he was using and endorsing a Parker central-fire. However, the breechloaders were slow to displace muzzleloaders, and it was common, even as late as 1875-76-77..., for muzzleloaders to out-number breechloaders in the pigeon ring, even at the biggest events.
John Bumstead, author of On the Wing: a Book for Sportsmen (1869) was critical of the new breechloaders, a was Joe Long in his American Wild-Fowl Shooting (1874), although he was willing to allow in his 1879 revised edition that breechloaders had their attractions.
In defense of the elder Greener, Daw's central-fire shell did not exist when he wrote his oft-quoted condemnation of breechloaders. Eley Bro's started making a Daw-like central-fire shotshell ca.1862-63, and the whole shotgunning equation changed "Over There." Meanwhile we were deciding "One nation or two," and after the war had some catching up to do. The Lefaucheux-type tiping breechloaders served as a template for some American makers of cheap guns, but the pin-fire shell never gained any popularity here.
I believe that N. R. Davis was the only American maker that offered a pin-fire in commercial numbers, and it was obsolete even as he started production. The tipping central-fire guns made by Parker (1867) and Whitney (1869) and Wesson (1869) and Ethan Allen (1869) were not the kind breechloaders the senior Greener was denigrating in 1858. I mentioned in my original post how the 2nd edition (1884)of W.W.Greener's The Gun is much different from the more commonly read 9th edition of 1907. Times change, technology changes, often very quickly. Let's not hold a man to what he said in 1858 by showing that he was less than visionary. A tipping breechloader was a bad bet when Greener had his say, however the part about the world being flat, he should have known better. EDM