A magnum is 1.5 litres therefore 2 standard size 750 ml bottles
The plural form for the noun derringer is derringers.
Some one will make you one if you offer enough money.
We need a make of derringer.
Anywhere from $25 to $300, depending on make, model, and condition. Most are worth $50-75, but a High Standard in VG condition would bring more.
No.The standard chamber length was 2 3/4in which was standardized in the year 1927.
Will depend on the make of derringer. They are not all the same. Would suggest you find a gunsmith to do this one. It is cheaper than taking one to them AFTER you work on it.
S&W does not make one.
depending on what parts you kneed a good gunsmith can make the parts you need.
Value of ANY gun is based on the exact make, model, and condition. We need all 3- you gave us 1. Sorry.
AFAIK, no one has tried to make an AR upper in 7mm Magnum
IIRC, they made a model called that.