I wouldn't shoot factory ammo at all regardless of stated dram equivalent. If you don't already have one invest in a reloading press and reload low pressure shells. That way you'll know the exact chamber pressures you're putting through the barrels.
No steel at all but you can reload bismuth or tungsten matrix if you can find it at a decent price.
He will not know the "exact pressures" with reloads any more than he will factory loaded shells, unless he sends a sample of them both to Tom Armbrust for testing. Reloading manual's pressures are only a guide, IMO.
SRH
