The 4 surplus rifles I was most disapointed in over the years were as follows.
The Israeli 308 Mauser.
A P-14 Eddystone .303. Grrr , loved that rifle but it would not shoot!
An A3 03 Springfield.
A Lee Enfield .303 WW2 ERA Australian manufactured #3, unfired.
They were all rebarreled except for the Lee Enfield III which was unfired.
I can't remember what ammo I fired through the 308 Mauser. I would have tried at least a few different manufacturers before giving up.
I was heavily into reloading rounds and buying rounds for .303. Those two 303rifles above had no excuse.
The 30-06 -- I tried several good type of rounds.
All the weapons wouldn't fire a 6" group at 100 yards bench rested.
Some of my favorites were the Swedish Mausers and my Lee Enfield # IVs.
The Irish contract # IV's Lees were spectacular. The one I scoped would shoot 3/4 groups with my accuracy hand loads.
I have 4 of those
one unfired.
I can not tell you why I had such bad luck with rebarreled surplus rifles.
The A3-03 was arsenal done - as was the 308.
I dunno?
None were two groove barrels.
I had an International Harvester M-1 a local gunsmith rebarreled and it was spectacular!!