Well, I guess I'm the naysayer that Calhoun was referring to. I've shot the .22 HP probably as much as any body has, and more than most. I've put thousands of shots through my selection of .22 HP's.
You can't just look at groove diameter, IMO. One must also consider throat diameter. With throats running to .229 (and larger) that presents even more opportunity for hot welding-temperature gasses to burn past the .224 bullet before it obturates to seal the bore. Out of five barrels I've done chamber casts on, one had a .228 throat, one had a .230 throat, and the rest were .229. Again due to analog manufacturing performed by actual human beings, chamber/throat/bore dimensions in these old rifles can be all over the map (and usually are).
Ten or fifteen years ago I would've blessed anyone seeking to use .224's in their guns due to the crappy performance of the only domestic bullet available at the time- the Hornady 70 grain spire point. John outlined its foibles succinctly. Now though, with boutique bullet makers offering jacketed bullets for the .227/.228 barrels there really isn't a good reason to use .224's IMO. Buffalo Arms, Reed's, Schroeder, all offer .228's in a variety of weights and lengths, most of which are suitable for Savage HiPower use. Cast bullet purveyors on GB continuously offer nice stuff too. Further, with a little creative searching on the Innerwebs one can scrounge up old discontinued Speer .227 70 grainers, Sisks of 50-70 grain weight, European offerings from Norma and RWS (just be careful of what you're buying), and leftover Hornady 70 grain spire points. If the Hornady's don't shoot for you, it's simple to make a file trim die to shorten their noses sufficiently to change that.
Ultimately though, the simplest/most elegant solution IMO is to snag a bullet mould and make your own and size them to fit the individual throat. They're cheap (almost free), accurate, and make the same size holes in paper that jacketed bullets do- and remember, rarely if ever has a barrel been worn out by shooting soft cast lead bullets, something to keep in mind when burning up a 100+ year old barrel that you like to shoot a lot.
