As Stimpy said, it's likely a special order model, I doubt it's a bull barrel, H&R has never offered a bull 30-06, but many don't know the difference in contours since the standard contour is heavier than most sporter weigh barrels, if it measures around .650" at the muzzle, it's not a bull, they measure about .800". It could also be an accessory barrel fitted to an Ultra or an Ultra stock on a Handi. Check to see if the last 3 digits of the serial number are engraved on the left side of the underlug, that will tell you if the barrel is factory fitted.
Tim