If it is not marked on the gun, you will have to measure it. The most probably calibers for an H&R revolver are .22, .32, and .38. A standard lead pencil will not go into the barrel of a .22, fit fairly well into a .32, and be loose in a .38, but don't run out to buy ammunition based on this estimation. Let a gunsmith or experienced dealer see the gun and recommend the proper ammunition (or recommend that it not be fired at all!). That patent date, alone, appears on the H&R Model 1 revolver, which is a single-action revolver with bird's head grip and spur trigger. It was chambered in both .32 Rimfire and .38 Rimfire. The ammunition is obsolete. sales@countrygunsmith.net
Consult with a good gunsmith.
25-150 USD or so
$100, more or less
$50-100, depending on condition.
No way to tell.
More information needed to determine model of firearm.
"BB" prefix indicates 1985
@ turn of the century; less than 100 USD
H&R made utility firearms from 1874-1986. 50-100 USD
1971
No such thing as 22 "caliper". 22 caliber, yes. 10-100 USD or so
50-100 USD