For value questions, it is best to search Gunbroker.com or gunsamerica.com. See what stuff is selling for...
5-150 USD depenidng on specifics.
50-125 or so
Best left to a gunsmith
Try e-gunparts.com, gun shows, internet, want ads.
Excellent condition: $325 fair condition: $150 Add $25 if you have both the .22lr and .22wmrf cylinders.
HR is Harrington & Richardson. They first made guns in the US in 1871. The company changed structure several times, and is now part of Remington.
50-150 USD or so depending on condition
This Model 676 was equipped from the factory with both a .22lr cylinder and a .22 wmrf cylinder - depending upon condition and barrel length (12" barrel commands a 20% premium) value will range from Excellent - $275 down to Fair - $75.
50-150 in poor to average condition. In Excellent condtion, with box and both .22lr and .22 magnum cylinders this model has sold in the $300 range.
No such model number in the S&W line
The H and R revolvers, produced by Harrington & Richardson, include several models, with the most notable being the H&R Model 922, a .22 caliber revolver, and the H&R Model 929, a .22 caliber double-action revolver. Other models include the H&R Model 676 and Model 738, which are chambered in .38 Special and .357 Magnum, respectively. These revolvers are known for their reliability and affordability, making them popular choices for both target shooting and personal defense. H&R revolvers were manufactured from the early 20th century until the company ceased operations in the mid-1980s.
50-100 USD