Any guess as to what caliber this is

[DubiousDan]

I found a couple old break top pistol frames in a box of stuff a friend left in my garage. On this one all I can make out is that it's a Iver Johnson. There's too much rust to make out anything else.

That's a 38 special sticking out of the cylinder. It appears as though the case length is about 0.79 inches, measured with calipers.

 

[JCC]

photos?

 

[msharley]

Hey DD,

That sounds to be a "38 Short" (38 Colt...etc)...

There were any number of small revolvers made for both the 38 & 32 Short...

(S&W was the 32 Long)

Later, Mark

 

[DubiousDan]

photos?

Thanks for the reminder.

 

[DubiousDan]

Hey DD,

That sounds to be a "38 Short" (38 Colt...etc)...

There were any number of small revolvers made for both the 38 & 32 Short...

(S&W was the 32 Long)

Later, Mark

There's a 32 S&W and S&W Long and a 32 Colt.

There was another complete break top in the box that I gave to a friend. It was 32 cal but I'm not sure if it's long or not. It didn't have any markings at all.

 

[rpwilson]

It is most likely a .32 S&W (short), you would need to make a chamber casting to be certain

 

[DubiousDan]

It is most likely a .32 S&W (short), you would need to make a chamber casting to be certain

Since it's straight walled measuring the length of the chamber would tell me if it's short for a 32 S&W long or measure the distance from the mouth of the case to the "thingy" in the chamber that would keep a too long cartridge (like the picture or the 38 spl) from going all the way to the rim.

 

[Moonpie]

38 S&W.

.38 S&W - Wikipedia

en.wikipedia.org

 

[Charley]

Agree. Given the cylinder length, and how far the 38 Special goes into the chamber, and how far it sticks out, 38 S&W is most likely.

 

[mongoose]

My Grandmother’s trusty I & J top break open with a chrome finish was a .38 short. Wish I knew what my Aunt did with it.

 

[SQLGeek]

38 S&W.

.38 S&W - Wikipedia

en.wikipedia.org

This is my guess as well.