This is a pretty cool little add-on - Hoptic USA's .357 Magnum Quiver
I suspect Hoptic made these to meet the demand from the tactical lever action crowd, but it works great on our Space Revolver.
The quiver holds 2x rounds of .357 Mag/.38 Special and has a small set screw on the underside of each loop that tightens/loosens the hold on each cartridge. The quiver's default attachment mechanism is M-LOK. We found that the screw that comes with the quiver threads into the threaded holes on the Kriss handguard so we're going to mount it there.
Hoptic makes the quivers for different calibers as well as in different colors. Black is the only color allowed in space. Here's how she looks on the Space Cowboy Revolver:
Hoptic's ammo quiver is the first that I came across for pistol calibers (others had made them for long range calibers). The company also has a 6-round quiver for pistol and rifle calibers (.357 mag to 45-70), as well as various other quivers for rifle calibers.
Since buying Hoptic's I've seen others release similar ones - including Ranger Point Precision 8-round Quiver (first image below), and Delta Mike's Summit Quiver that comes in 2- and 3-round versions (second image below). All of these quivers attach via M-LOK, which makes sense as most of the tactical lever action crowd is running M-LOK handguards.