Neither the DANFS entry, nor the entry in Silverstone's volume indicate that the armaments were changed, at any stage, so, unless a change went unrecorded, I would assume that the vessel did keep the same armaments throughout. I guess the only other way to check is to go to the daily entries in the deck logs, but this would entail an expenditure for copies of the log, and a perusal of each daily entry, for the two years.
I assume that you have checked the dispatches relating to the engagement in both the Army, as well as the Naval Official Records. Sometimes, as I have found in cases where both Army and Naval forces were involved in an engagement, the Official records of either force do not always contain exactly the same reports, and one can sometimes come upon some gems.