Guns aren’t even the most efficient way to influence a government, bombs are. The IRA’s vehicle bomb attacks was more effective than any gun attack. They’d smuggle in precursor chemicals from abroad and patiently build their bombs before targeting government and financial centers.
They’d give a telephoned pre-warning to authorities so civilians would be evacuated. With each bombing the economic impact was getting higher and higher. Insurance and taxes were increased, this made the government very unpopular with the people.