Looks to me it's identical to many excellent barrels that were reamed to finish bore diameter after gun drilling the barrel (evidence is the micro grooves at right angles to the bore axis across the tops of the lands) then rifled (evidence is the lengthwise tinier micro grooves in the bottom of the lands at groove diameter) such that the rifler didn't take off any metal atop the lands.
I shot many a 7.62 NATO Garand barrels that looked exactly like that. Gun drilled, reamed then broach rifled; all 4 grooves at once. They easily shot no worse than 1/3 MOA at 100 yards, 2/3 MOA at 600 with jacketed bullets. Their bore diameter was .2995" and groove diamter was .3078" to .3079".
If your barrel's groove diameter is a bit smaller than jacketed bullet diameter, it may well drive tiny headed tacks. Shoot that barrel to see how it performs. It looks good to me.