"the hammer just flops back and forth. Hammer spring?"
Hopefully that's all it is.
If the hammer is broken internally you might have a very difficult time finding another one.
If the barrel is roughly .32 caliber and it's centerfire, the chances are excellent that it's .32-40. That was one of the most popular of the Ballard calibers, surpassed, I believe, only by the .38-55.
We really need pictures.
And, my curiosity is killing me.
How much is a garage sale Ballard going for these days?
"The gift which I am sending you is called a dog, and is in fact the most precious and valuable possession of mankind" -Theodorus Gaza
Baby Jesus cries when the fat redneck doesn't have military-grade firepower.