I think for both reasons. Under that moniker so far they can still only be chambered by JD (although a close copy could be made and called something else like was done with the 375JDJ/375-444 for years). I've had two 6.5JDJ barrels, and it is a fun little wildcat. In my case I liked my two 257JDJ's better though (probably because my 6.5 Super Bower is my favorite in that caliber). I've had several other JDJ calibers over the years as well, but my all time favorite from JD was the four 375JDJ barrels I've had. Mine have all been SSK barrels, not rechambers.