I read a British Army report on confiscated weapons after the "Troubles" officially ended and there was a disarmament. IIRC, AR15s outnumbered AR180s by a significant margin. Huge numbers of AK47s and AKMs were also confiscated, due to the Libyan connection of the IRA. A deputy I worked with had been a "Boy Soldier" with the British Army (went in at 16). He did a long hitch over there, and said AR15s still gave him the creeps.. He married an American gal, and became a US citizen after he got out of the Army. Then he became a deputy in California.
I grew up an Irish Catholic in Chicago in the 50s and 60s. IRA sympathies were the norm in the Irish American community, and Irish priests would rail on the "godless English occupiers." I knew even as a teen and young adult around 1968-72 that guns were being bought all over the midwest and east coast to be smuggled to Northern Ireland. Even in the early 70s, I heard that "Armalites" were very desirable, and hard to find in sporting goods stores there.
Politics of the of past aside, unfortunately the IRA became an army without a war, and a large number turned to organized crime and drug trafficking, according to my cousins (also Catholics) over there. They no longer enjoy the unconditional acceptance of fellow Irish Catholics, who have begun to like "the peace," and realize that they morphed into terrorist and gangsters. They are still afraid of them, though.