From a reader…
One of our parishioners posted this image on his facebook page and I commented, “Hey, if you have guns you want blessed, let me know.” Low and behold he took me up on the offer. That is why I asked if there was a blessing of guns.
This is great!
There are blessings for all sort of tools and a gun is just a tool. They are, in themselves, morally indifferent. They can be blessed. We can ask God to be especially mindful of their safekeeping, for their proper function, that they not be used for evil purposes, and, in the case of your guns, bows, trebuchets, etc., that each projectile fired with them may find your intended marks.
There is no specific blessing in the Roman Ritual for blessing guns. However there is a blessing “for all things”.
After the usual introduction, the blessing prayer is…
Deus, cujus verbo sanctificántur ómnia, bene+dictiónem tuam effúnde super creatúram istam (creatúras istas – PLURAL, of course); et præsta, ut quisquis ea (eis) secúndum legem et voluntátem tuam cum gratiárum actióne usus fúerit, per invocatiónem sanctíssimi nóminis tui, córporis sanitátem, et ánimæ tutélam, te auctóre, percípiat. Per Christum Dóminum nostrum.