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Bumping again.
The Calico M-100P has nothing particularly noteworthy going on about its action, it's, straight blowback, basically an upside down Ruger 10/22 action. What makes it interesting is the magazine, which holds 100 rounds of .22 Long Rifle, the followers in the magazine forming a helix, hence the term 'helical magazine', which is almost like a drum stretched front to back.
These guns can be slightly temperamental because of their complex magazines, but if you use hot and good quality ammo like CCI Stingers, clean the gun every couple hundred rounds or so, and wind the magazine an appropriate number of times when filling it, you should have no problems. The rear sight is mounted on the magazine, which technically wouldn't be conducive to repeatable precision, but it doesn't seem to make a difference. This pistol specifically is more than anything a gun for fun plinking, rather than serious competition or combat.
Famously, these are available as a weapon in Resident Evil : Code Veronica, where you can find a pair of these pistols. There's no spare ammo for them, but each of them are fully loaded, thus that is 200rds available to the player very early on, they aren't the strongest of course, but bullets are bullets, and they have the added gimmick of you being able to aim them individually with your analog sticks. How worthwhile that gimmick is, I couldn't say, I never got around to playing that game. All I hear though is that Code Veronica is a real mess of a game and not that good, however.