Thats a nitrous cracker.
A good one, too.
You should not keep that near your guns
They are considered drug paraphrenalia by just about every PD I know of.
I could have answered that one a lot earlier....dang studying.
My apologies for not being omnipresent.
That one is designed for what are called "bubbles"- the large diameter cartridges used in oversized 3 liter dispensers used where a standard cartridge would not correctly dispense the entire contents of an industrial sized 3l whipped cream dispenser. - Although it can be used for standard cartridges as well. Thats why you need the twist handle- they have a thicker seal, and require more force than most kids can get in a hand two piece cracker.
To use........
Put a baloon on the bottom.
You insert the cartridge, depress the actuator ( the pointy part) by sealing the two halves together- or in this case the twist handle.
Untwist the handle, and the cartridge ventilates under pressure out the holes into your baloon.
Theres your hippy crack explanation for the day.
G'night gents........
The only thought I could have on why this might be in reloading gear is that they can also be used to safely unpower compromised c02 cartrdges that you would not want to install in an air rifle.
I'm totally sure thats why its there.
Final note : The fact that this is the first question that I could answer with some authority, that RC could not, in the H+R forum, based on a picture, does not escape me. This exposes the generational gap, and yet another reason that "youngins" need to be involved in the process........not everyone will have all the answers- forever. You are forgiven, RC- for not being able to correctly identify drug paraphrenalia.
Or, its not that at ALL- and just bears an uncanny resemblance to one in every respect imaginable.
PPS : The threading on the bottom is used for attachment to a pressure receptacle- like a 3l whip cream container with a one way pin valve......