On the whole, cheapest firearm you could have is a deficited small smoothbore.

But, even if you do manage to bring the cost down to twenty starbux, is it a worthwhile buy?

The ammunition costs a starbux, for three dice minus two, at sixty metres; light rocketified rifle rounds are two dice at two hundred fifty metres, costing four fifths of a starbux.

Bulky versus zero gravity; rifle barrel versus minimal barrel.

Range zero to ten (short), eleven to fifteen (short minus two), sixteen to sixty (effective minus two), sixty one to one hundred twenty (long minus two), one hundred twenty one to two hundred forty (extreme minus two).

Range zero to ten (short, one dice), eleven to sixty two and a half (short minus one), sixty three to two hundred fifty (effective minus one), two hundred fifty one to five hundred (long minus one), five hundred one to a thousand (extreme minus one).

Also, rockets are inherently caseless, whereas shotgun shell has to be ejected.

The rocket bullets cost double at eighty centimes, compared to forty for twenty two long rifle, but same as with the shotgun, you need a rifle length barrel to achieve sixty percent rocket range, whereas minimal for the rocket. Shotgun extreme reaching two hundred forty metres at minus two, which is effective for the rocket at minus one, effective range at sixty, is short range for the rocket.

Likely inaccuracy two plus bulky one, against inaccuracy minus one, plus zero gravity.

Default capacity about five or six, versus eight or nine.