Various terms are thrown around by anti-gun activists. "Assault weapon" might mean any weapon capable of taking a large capacity magazine, any weapon with design features similar to military weapons (pistol grip, flash hider, bayonet lug, folding stock) etc, etc, etc.
"Legitimate sporting purpose" is another handy term. If a rifle is not capable of a high degree of accuracy, it obviously has no "legitimate sporting purpose". Of course, if a rifle is capable of a high degree of accuracy, then it is a "sniper rifle" (especially if equipped with a telescopic sight).
"Military weapons" is another handy euphemism. Any weapon that has ever been used by military forces will be argued as unsuitable for civilian uses or ownership. This creates perhaps the broadest net for the gun-banners because, at one time or another, our miliary forces have used single-shot rifles and multi-shot rifles, all manner of shotguns, rimfire and centerfire weapons of all types, handguns including revolvers and semi-autos, breech-loading and muzzle-loading weapons, easily concealed weapons as well as crew-served weapons, just about everything from slingshots to cruise missiles can be described as "military weapons".
A number of other countries ban civilian possession of any weapon chambered in "military calibers". This easily provides another avenue for the gun-banners. At one time or another military forces have used every conceivable caliber of muzzle-loading weapons from 5mm to .75 caliber or larger. Rimfire cartridges from the .22 Short through 9mm and larger were specifically developed for military arms. Centerfire cartridges that have been used by military forces include at least 75% of all such cartridges ever produced.
Just in my lifetime I can recall just about every category of individual weapon having some role in military use, including pistols and revolvers in .22, .38 Spl, .357 magnum, 9X19mm, .44 magnum, .45ACP, .45 Colt, 5.56mm NATO, 7.62mm NATO, .30-06, .30 Carbine, .276 Pedersen, .50BMG, 7.62 Russian, 7.62X39mm, 5.45mm, 6mm, 7mm, 7.35mm, 7.65mm, 7.92mm, 8mm, multiples of 9mm cartridges (all developed for military weapons), 10mm, 11mm, 12mm, 12.5mm, and others.
Revolvers? No doubt about it. The ubiquitous S&W K-frames derived from the 1895 model, which was known as the Military & Police model for decades. Colt O-frames developed from the 1890's "Army" and "Navy" revolvers and include the newer Official Police, Trooper and Python series. The S&W Model 29 .44 Magnum (with multiple modifications) saw limited service in Vietnam for clearing bunker and tunnel complexes. The Colt Single Action Army revolver was specifically developed for the US Army in 1873, so just about everything that followed that general pattern can be lumped in.
The Remington rolling block single shot rifles and pistols were military arms, widely distributed and used throughout the world.
During WW2 the US sent many Remington "Rangemaster" .22LR match rifles to the Soviet Union, intended for riflery training but used to great effect as urban sniper rifles.
One of the key US Supreme Court cases involving the 2nd Amendment established essentially that since short-barreled shotguns had never seen significant use for military purposes, therefore were not subject to protections for civilian purposes and properly banned by the National Firearms Act. Since then, however, US armed forces have made wide use of very short-barreled shotguns (Remington 870 variants) for breaching doors and barricades, so it would appear that this position is open for reinterpretation.
Literally every type of firearm, and every caliber of ammunition, was either developed for or derived from military applications. Those who seek to infringe 2nd Amendment guarantees via "reasonable restrictions" can support just about any infringements on these types of arguments.
No firearm is safe or immune from the zealots.