Today Crosman air gun company owns the rights to the Hahn BB line of air guns. The rifle was made between 1958 to 1971. See the link below for a detail drawing of the parts.
How do you put WHAT. A pellets in the rifle, a BB in the rifle, Put it back together. your question is incomplete.
Gun shop or gunsmith
WATER
Into the clip or magazine on the underside of the rifle, in front of the trigger
You get an explosion.
Go to www.crosman.com and click on "Download a manual" you will find you rifle there. It will give you an exploded view of the rifle.
See the link below for the parts diagram.
put organic soap and bleach together the put a suchen cup under the lid then put a hole in the lid then put paperclip pin then you got a musterd gas gernade.
Take a bite of humble pie and ask a gunsmith for help.
Put the Rifle Down was created in 2003.
The JC Higgins Model 21 is a pump shotgun, not a rifle. Reassembly should be done by a competent gunsmith.
The best thing do with that is not to do it yourself. Call the gas company and they will come out and hook up the gas line for you for no charge.