Ah Raggy you cannot be bothered to research stuff and look it up yourself.

From any internet article relating to HMY Helga you will get the following information:

HMY Helga was based out of Dún Laoghaire and on the night of the 25th of April, 1916, the Helga was ordered up the Liffey and to shell Liberty Hall with her 12 pounder gun.

From RTE Chronology of Events:
20.15 – British gun yacht, the HMY Helga has entered the Liffey and fired (2 shells) at Boland's Mills damaging the upper storeys.

The following morning on the 26th April 1916 the same source has HMY Helga shelling Liberty Hall between 08:30hrs and 12:00hrs when 24 shells were fired.

The 12 pounder gun on Helga was then assigned targets in Sackville street at which she fired 14 shells after which Helga played no further part in the proceedings apart from unshipping and landing a 1 pounder gun for use ashore by the Army.

If I remember correctly it was the discrepancy concerning the dates that blew your "Volunteers" artillery duel hogwash to bits.

So unless you can come up with some factual evidence to the contrary I will stand by my statement at the time the first fires were started in Sackville Street on the evening of the 24th April 1916 the British had no artillery in Dublin.