Not much of a collector's market for these. Rarely go over 125.
The value of a IV FR Johnsons arms 32 caliber Fitchburg mass revolver is actually dependent upon a number of factors. Most important of these factors would be the condition of the revolver.
the serial number is under the grips
The earliest patent for a revolver was issued in 1818, for a flintlock revolver. There were other patents for revolvers, but the most significant was the Colt patent, which issued in England in 1835 and in the US in 1836. The specific thing that was patented was not the revolver, but a revolver designed in such a way that the cylinder was rotated and locked by the action of cocking the hammer.
gatlin
model 1900 fitchburg mass usa A38473
The revolver is probably an Iver Johnson. The grips were after-market grips, distributed by Siles.
Sounds like a Remington-Beals Army, depends on condition, condition, and condition. The variance is so large based on this to even give a guess.
The western style .22 caliber 8 shot Iver Johnson revolver began production in 1968. This gun is most likely from the late 1970s. They are valued at about 150 dollars in average condition.
You have not given us the make, model, or condition. Some aspect of your gun was PATENTED ( abbreviated as Pat.) on some date in the month of June. We need some clues to get you a meaningful answer.
If it's in very good condition, maybe about $125 or so. I have one and it is very accurate.
Colt Paterson, the revolver was patented by Samuel Colt on February 25, 1836 in the US.
depending on condition of your revolver it would be worth 775.00 dollars in 50% condition up to 1,000 in 70% condition.