my headcanon: Riza instructs everyone in proper firearm usage and always reminds the guys to clean their guns regularly. Roy organizes a quarterly refresher course on marksmanship and gun maintenance. The team makes it a competition every time. Whoever loses has to buy drinks for the others afterwards. With all that training, everyone is fairly competent with firearms – including Roy since Riza insists he should know how to shoot accurately despite having his Flame Alchemy (so he isn’t so useless even when wet!).
basis: Everyone (with the exception of Falman, who - according to Havoc during the “fishing” mission with Barry - barely had experience on the field) was proficient with guns. In the 3rd Laboratory, Roy was able to target specific points on Lust in his attempt to disarm her, which shows that he has decent marksmanship skills.
“Humankind cannot gain anything without first giving something in return. To obtain, something of equal value must be lost. That is alchemy’s first law of Equivalent Exchange. In those days, we really believed that to be the world’s one, and only truth.”
↳ This portal… I know it contains every secret alchemy has to offer. However, it’s also lead me astray. I saw the truth that lies within it and I became convinced I could solve everything with alchemy. But I couldn’t possibly have been more wrong. That was just arrogance.