They were made using the melted down blue-grey steel of the sword, Excalibur, and have the rose, the sign of the Eld, engraved in the side. The sandalwood grips of the gun have never lost their fragrance and near the muzzle of each gun can be seen scroll work which translates to "White", which was Arthur's dinh mark.
However, there are many other legends regarding their origins, and some say the steel and sandalwood are not from Mid-World but brought from an alien world. Others believe the guns came from same Kashamin pyramid that Arthur and his sword Excalibur have been entombed in; others say they were a gift from the Dark Tower.
The guns are extraordinarily large by the standards of modern pistols. They are described multiple times as being "comically large". The guns shoot .45 caliber bullets and our world's equivalent of Roland's original bullets are Long Colt .45's.
A few times in the series, Roland has referred to the guns as "the widow makers".
As Roland had to present a sign of Arthur Eld upon entering the Dark Tower, he presented one of the sandalwood guns, which allowed him access (the other having been taken by Susannah when she left to find her own world and her own destiny). He originally wanted to present the Horn of Eld, but he lost it after The Battle of Jericho Hill.
From the way they are usually depicted and described, they are likely twins of the Colt Single Action Army model, otherwise known as The Peacemaker or the SAA in .45 Long Colt. or maybe a .454 casull like this one []
But in Midworld, anything is possible.
Historical analysis and hypotheses:
First of all, the .45 bore diameter for ammunition was widespread in the 19th century, and was used by a large number of gun and ammunition manufacturers.
In the books, Roland was able to purchase off-the-shelf ammunition for his guns in New York in the 1970s; but their designation was fictional (Winchester .45), and if anything, inconsistent. Since Stephen King, sometimes on purpose, sometimes inadvertently, glosses over realistic considerations for such matters, the ammunition cannot be a pointer for identifying Roland's guns.
Similar dead end is the Jake's Ruger .44 automatic — no such gun ever existed, but the archetype is clear, and speculations are possible to connect it to iconic semi-automatic magazine-fed pistols like Wildey Magnum or AutoMag.
What follows is mere speculation.
- Roland is modeled after iconic Old West gunslingers, as depicted in revisionist Westerns (namely, a variation on Sergio Leone's Man with No Name). These silver screen gunslingers used revolvers of the second half of 19th century, either cap-and-ball, cartridge conversion, or early cartridge ones (like Colt SAA). In any case, his revolvers are of the Old West era, and seem to be conservative even for that era.
- Roland's guns are described as unusually, strikingly large and archaic — even for regular Mid-World people who use firearms not far removed from old-timey Old West pistols and rifles. The stress here is on "large": they are so bespoke and ornate that "archaic" or "obsolete" does not really apply.
- Roland uses cartridges, but loads them into the gun in an unspecified way. The books never explicitly specify if Roland flips the cylinder out and extracts cases in one go.("Roland tipped out the cylinder of his gun, dropped the spent casings around his boots, and reloaded." The Dark Tower VI: Song of Susannah). Most likely King was not bothered by such minutia. But for identifying guns, this is important. Flip-out cylinders are the mark of modern revolvers ("modern" meaning after the end of Old West era). Before that, people either loaded each chamber with powder and ball, then seated caps (obviously untenable for Roland's lightning fast reloads), or reloaded cartridges one by one through a gate (open hole on the side, displaying one chamber at a time).
Now let's summarize the data.
- Roland uses mid- to late 19th century revolvers, with the possibility of being conservative (i. e. using something from the dawn of US Western revolver era).
- Roland uses cartridges (brass things that have casing, bullet, primer. and powder in one package, portable and handy to reload quickly).
- Roland's guns are incredibly large. Their power is merely the consequence of their size (this will become apparent later).
Before making any assumptions, let's look at the left side of the page: there's Idris Elba, who's armed with Remington 1858 New Army revolvers which are modified to work with cartridges and flip out the cylinder. His guns are comically large, archaic, Old West, but also load like modern revolvers. This is a compromise that the movie's armorers decided to make. It satisfies all the criteria of what Roland's guns are. But if a hybrid, what would be the thing that the book Roland had used?
The iconic "huge revolver" of the Old West era is the Colt Walker: the first actually popular Colt revolver that looks like a Western revolver to our eyes. It was indeed huge, and intented for use by cavalry in saddle holsters. No one really tried to haul these in their pants. Its size is more reminiscent of a truncheon.
The continuation of Colt Walker aesthetic is the Colt Dragoon. It is still really huge, but is more manageable. In True Grit, much fuss is made about how it's too large for a smallish person to fire. Still, it is halfway to cowboy revolvers as we know 'em.
After that, comes Colt Navy 1851, the so-called "Belt Pistol", in .36 caliber. This meant that the revolver could be hauled on a belt. It still very much resembles the Walker and Dragoon behemoths, only smaller and more graceful (some put it on a pedestal as the most beautiful revolver of the Old West; Wild Bill Hickock seemed to agree, since this was what he carried all his life).
Then, the era of Colt Single Action Army begins: the relatively compact, svelte pistol, developed from the ground up for use with newfangled metallic cartridges. It became a movie star, and is now forever associated with nickel plating, corny lines, and gun-juggling.
Thing is, The Man with No Name actually carries a Colt Navy 1851. It must have been seen by Leone as sufficiently no-nonsense and old-fashioned for him to use. And it is: it looks nothing like today's revolvers, and invokes the spirit of unconquered West. It's reasonable to think that Stephen King would agree, since Roland's revolvers are seen as old-fashioned and exotic.
It is also in the right historical spot: Colt Navies were cap-and-ball, but could be later converted to cartridges. In a Colt SAA world of the 1870s and 1880s, you would look stalwart and conservative using one, but it would still absolutely do the job.
Finally, Colt Walkers and their kin today have the aura not unlike family guns of the line of Eld: there were so few of them made (compared to mass-produced Colt SAAs, Rem 1858s, and other army-issued pistols), that they truly fill the role of inherited, historical, precious relics.
- It is most likely that Roland's revolvers looked similar to Colt Walkers or Dragoons (the guns famous for their imposing dimensions). This also allows ample space to put all the ornaments that are described in the books. Colts from Walker to Navy have a large space on the massive, old-fashioned octagonal barrel, that could be decorated with roses and whatnot. Other Old West revolvers don't have that space (Rem 1858 has a curved airy frame, and SAA is round and compact all around).
- Roland's guns were obviously fitted for using cartridges, so there are no exact matches in real world. Since they're Dragoon/Navy lookalikes, they could only be loaded one cartrdge at a time. This fits with the books: one thing is to slap a speed-loader into a flip-out S&W cylinder, another entirely is to train for years to reload a gate-loaded revolver in seconds. This is why gunslingers are legendary: they can flip cartridges into the awkward loading gate in a blur, like a factory machine.
- As for the caliber, this is a non-issue, since Roland's guns are fantasy hybrids anyway. Revolvers of the Old West and Civil War era were offered in a plethora of different calibers, and the consumer could select one according to their tastes. The reader can choose whatever metallic cartridge caliber they like for Roland's guns, be it .45 Long Colt, or some of the high-powered cartridges like 45-70 Government or .44-40 Winchester that were used in the post-Civil War era. Considering that Roland's guns are bespoke and notoriously destructive, the latter would be likely. This is also consistent: in the 1970s, you could indeed buy black-powder 45-70 cartridges in a fairly well-stocked American gun store: they were used by old-fashioned folks and old gun enthusiasts. .45-70 is still produced and used by the same.
NOTE: So what about the power?
It was remarked previously that Roland's revolvers are only as powerful as his guns are large. This is because before the era of smokeless powder, everyone used black powder. It burns slowly and has a limit on the energy it can output. What it means is, people could only make guns more powerful by making them shoot larger bullets. It is definitely not true now: velocity is king when it comes to power, and modern gunpowders can propel bullets to speeds that make even tiny 5.56 mm bullets into formidable agents of destruction. But in the era of "Roland's" revolvers, bigger was better. So even though his old-fashioned revolvers only shoot bullets at relatively slow velocities, the bullets themselves, and the powder load behind them, are huge. This is reflected in the books: Roland's shots summarily destroy head, limb, and object — simply because their projectiles are chunks of lead that rival those of modern shotgun slugs. (Although, one contributor notes that Roland's bullets were not necessarily slow- the Walker Colt with its original load of 60 grains of black powder propelled a 146 grain round ball at 1350 feet per second. This is a similar velocity to a modern .357 magnum round. With those long barrels, and a .45 slug, those guns may have been very powerful indeed loaded with smokeless powder, which their cylinders could apparently handle).
In the end the compound picture of Roland's guns would be a gigantic Colt Walker or an enlarged Colt Navy (Clint Eastwood style), made for metallic cartridges, loaded through a gate, and chambered for a black powder monster rifle cartridge from the Old West era, like 45-70.