Assuming you mean a Sterling mdl 287 PPL in cal. .380, these retailed new for about $90.
Make, model, condition. We need all 3 factors.
Best left to a gunsmith
$50 - $80
there is no such thing
100-1000 depending on specifics
$150 or less, depending on condition.
You can only use .380 ACP ammo in a .380 pistol. Period.
I could not find any 380 cal. pistol going back to 1887 ??? are you sure it's not a 38 cal. revolver ???? check writting on top of barrel ......................
15-75 dollars
$75-$100 Depending on condition
A Sterling Model 300S is about $90-$130, depending on condition.
50-350 USD or so