I'm by no means an expert, but I still have an opinion! Generally, such lists seem to represent some sort of popularity contest, rather than gauging just what was influential and what wasn't.
For instance, the list has, at #4, the Colt Single Action Army. So what, if it was "iconic" in the Old West? This may have had an impact on movie making, but I don't see how the Colt Single Action Army would be "greater" than something like the original Colt Paterson revolver, which was the ancestor of all modern revolvers, being a significant advance over the previous multibarreled "pepperboxes." All of the later cartridge, double action, break open, and swing out cylinder designs are all variations on Col. Colt's original Paterson revolver.
What the S&W Model 29 is doing in the list of the 10 greatest guns is beyond me. Perhaps the author needs to stop fantasizing over
Dirty Harry movies.
Now, where on the list is Alexander Forsyth's first percussion ignition shotgun? That gun had such an influence on firearms that it ended the near 200 year reign of the flintlock and it's principle of a percussion primer is still with us in modern cartridge guns today. That's a lot more influence than ANY other gun on the list, and it's not even there!
The .44 Henry Rifle might be a good candidate for this list, based on it being an influential cartridge weapon that was also repeating. It may be objected that the Spencer rifle, which was also repeating and also used a metallic cartridge, deserves an equal place, however the Henry was clearly the more influential rifle. (Noting here that the Henry action was really a perfection of Wesson's Volcanic pistol action, the toggle link was a very weak system that survived only to the Winchester 1876 model. Later Winchesters were Browning designs. The Spencer would be more akin to the Savage 99 in action design. However, note that the Spencer still had the big, old-fashioned side hammer, while the Winchester/Henry was self cocking.)
The .50 BMG: Perhaps this COULD be on the list, but not for the reason the author suggests: "The Browning Machine Gun is chambered for the most awe-inspiring shoulder-fired cartridge to date." Such talk would well qualify for what one of our US presidents would call "Bloviating." I think the British term would be "3 bags full." Anyway, cartridge similar to the .50 BMG was used by the Germans in WW1:
http://en.wikipedia.org/wiki/13.2_mm_TuF
In a shoulder held rifle:
http://en.wikipedia.org/wiki/Mauser_1918_T-Gewehr
Also a machine gun was chambered in this round:
http://en.wikipedia.org/wiki/MG_18_TuF
The British also had the Boys anti-tank rifle in WW2:
http://en.wikipedia.org/wiki/Boys_anti-tank_rifle
And there were others that could be mentioned. Here's a list of .50 caliber machine guns to ponder:
http://en.wikipedia.org/wiki/Category:1 ... chine_guns
The author is clearly guilty of bloviating here.
However, this is not to say that the .50 BMG, cartridge or weapon, was not influential. Whether it deserves to be listed in the top 10 may be questioned, but the fact that it has been in service for such a long time in front line use, and especially its contribution to the gun power of US aircraft in WW2. (it hit so much harder than the rifle caliber machine guns favored by other powers, and usually had a faster rate of fire and better ballistics than 20mm and up cannon of near equivalent weight. When the fighter age turned to jets, multiple harder hitting cannon were needed, but in the WW2 era, the .50 BMG was hard to beat for aircraft armament.) It's to be expected that a Browning design was so reliable -- he was truly a genius.
The author's Mauser ramblings: Actually, I would say that it is the M98 against which all other actions are compared, not the M93. And, the M93 was actually a transitional design, which began with the M89 Belgian rifle. Several other models predated the M93 and several post dated it before the M98 perfected this line of designs.
There is the Lee-Enfield design, but it was the culmination of the work of James Paris Lee. Here, the author is curious: He picks an intermediate design of Mauser to represent that design thread, but for the Lee-Enfield, he says that it was in service from the Boer War until 1957, a period in which a number of Lee-Enfield designs were used by the British Empire, but which the major examples, the SMLE Mk III and the No. 4 Mk I were intermediates are not mentioned -- the opposite of his Mauser talk.
As for the 3rd design he mentions regarding bolt action rifles, the Mosin Nagant is not what I would think of as a unique design. The action is fairly similar to many pre-Mauser designs in Europe. Mosin included some of his own ideas, some of which may have been to reduce dependence on foreign patent rights, or he may have wished to avoid using the bolt take down screw common to many of those other designs. Also, the Nagant part of the name is just what it says: the magazine was the design of the Belgian arms designers Leon and Emile Nagant. I am known in some circles as being an aficionado of the Mosin-Nagant rifle; this is a valid accusation. However, while unique and interesting, I wouldn't exactly name it as a type of major design, unless one was basing the classification on sheer numbers produced.
This brings up a complaint I have: the author of the article doesn't seem to pay any attention to seminal influences on gun design. He appears to have an odd mixture of recent popularity and personal favorites in his choices. There's certainly nothing wrong with favorites -- I've got mine, as well. But calling them the greatest is another matter.
Still, it is an interesting subject.