It depends on the thickness of the barrel, but you can have barrels cut, rethreaded, etc.
<span style="color: #FF0000">True,it can be done </span>
I don't like threading adapters. Just adding threading error (loseness) upon error.
<span style="color: #CC0000">Very true,this is the exact reason I dont like them.So if you can,get both barrels threaded for 5/8 x 24 </span>