Ranchero's of the past ( Say @ 4-5 years ) or older used LW barrels as did all FX's. Pretty sure when FX dumped all the LW barrels threw AOA and went smooth twist it covered every model produced after this time period.
Mine really likes the JSB 15.9gr pellet. I use it for everything from 10 - 45 yards and it is very accurate from the Smooth Twist. I've regged mine with an Altaros and push them at 650fps.