The WoI and later CW were fought using smallarms because only that type was available, mainly through capture (RIC Lee Enfields) or robbery (shotguns & stalking rifles). Most of the small volume imports came by courier from Glasgow, etc. Even then ammunition supply was an issue, both in quantity, quality and because of mixed calibre. ‘Republican’ imports matter little, in 1913/14 they imported about 1500 rifles and 30k rounds of ammunition, all obsolete Mausers from the Franco-Prussian war of 1870/1. FWIW in the same era the ‘Loyalists’ imported about 40,000 rifles and 3 million rounds.
Most of the ‘Republicans’ had no idea of firearms beyond a cursory knowledge of shotguns; very few would have been able to strip, clean and reassemble the action of a rifle or pistol.
Anyone with even a superficial knowledge of the BMH statements would realise that drawing comparisons between that era and post-1970 events in NI is stupid and worthless. It also shows a complete lack of understanding of the very obvious differences in the arms procurement and training processes available in the two periods. Also, the Old IRA people I knew had zero tolerance for the Provo's etc and their antics in NI.
These are just the sad facts of war, every war, even the Franco-Prussian war you mention, civilians are killed by both sides. I can't think of a war/conflict in the 20th & 21st century which at least 500 people died that both sides didn't kill civilians in. Spanish civil war, Russian civil war, WW1 & 2, all the Latin American conflicts, The Irish civil War, the Syrian civil war, The Troubles, the Basque conflict, the Lebanon civil war, the Israel - Palestine wars, Aden, Suez, Malaya crisis and I could be here all day, but you get the point each side in those conflicts killed civilians, some killed dozens, some killed millions, this is just the sad fact of modern day capitalist imperialism, hopefully one day we will live in a world were nation states will become democratic, but at the moment that seems very unlikely.
Also that attitude of
Old IRA = Good
Provo IRA = Bad
Is just stupid & arrogant at best and triumphalist & supremacist at worst.