Well I'm assuming you mean the Champion 12 gauge single shot?
If so by the cocking pin there is a lever that moves vertical left from right. Turn the lever right an the barrel breaks. (The lever basicaly right on top of the stock )
age Iver Johnson shotgun serial # 33743
Iver Johnson
$25-50.00
Iver Johnson did not have a 410 gauge or bore in 1907. The 410 came along about 1920.
50-100 USD
I'm not sure if it's a champion but I do own an Iver Johnson 24 gauge shotgun...single break action...I beleive they were made between 1909 to 1913... my grand father first gun at 14 yrs old...
$50-$125
Ivory johnson 16 guage chamion shot gun
Model 1901 Iver Johnson, semi-hammerless, automatic ejector single gun.
Yes Iver Johnson did make 410 shot guns, I own 2 break open 410 shot guns both made by Iver Johnson.
My best guess is $350
About $600-700 in very good condition.