Powder fouling left in the barrel is not an issue just as it wouldn't be with any other rifle.
Plain water (preferably hot) will dissolve the corrosive primer salt. Some guys use Windex, not really necessary IMO.
No way you did any severe damage to the barrel in a week's time, but you need to dissolve the salts completely, clean and then lightly oil the bore before you put it up.
Do a search, many discussions on this. Never a consensus (window cleaner, water, Hoppes #9) just like barrel break-in and "normal" barrel cleaning.
Me, I take a vial of Windex/water to the range and pour some down the breech after shooting, and then hot water down the bore followed by cleaning and an oiled patch when I get home when shooting corrosive ammo.
And.. don't forget about the boltface...