Found this on Al Gore's internet.
here is the information i have on this series of H&R bolt action rifles. the model 330 was manufactured during the time FN actions were used. none of the catalogs say anything about what barrels were used. i do know that the model 317 used premium grade barrels but the model 330 is listed as a hunting grade. there is a very good chance your rifle has a douglas barrel but i doubt it is one of their premuim grade.
most of this information is also found in the 30th edition of the blue book.
MODEL 300 ULTRA BOLT ACTION RIFLE--1965-1981
Bolt Action Repeater, Mauser Action, Centerfire calibers 22-250, 243, 270, 30-06,308, 300 Win. Mag,, 7mm REM. Mag., 3 or 5 Round Internal Magazine, Barrel Length 22 inches, Drilled & Tapped for Scope Mount, Ramped Front Blade, open Adjustable Rear, Hinged Floor Plate, Adjustable Trigger, Checkered American Walnut Monte Carlo Stock with Roll-over Cheek Piece, Full Pistol Grip, Contrasting Wood on Pistol Grip Cap & Fore-end, Blue finish, Recoil Pad and Sling Swivels, Weight 7¾ Pounds, Overall Length 42½ inches.
Three different Mauser Actions used during production of this and other Models.
1965 – 1972 Mauser type action from Fabrique Nationale in Belgium
1973 – 1977 Sako actions from Finland
1978 – 1983 Mauser type Mark X action by Zaslava in Yugoslavia. The exception to this is the Model 317 and 317P (1968-1974) always used Sako actions.