DH is an infantry soldier and gunner by trade DS will grow up knowing the influence of guns in his dad's life, when we go to RAF families' days the guns are out on display for people to see how heavy they are etc, it's not something we are ashamed of, it is part of our work community and defends this country and we are proud of this. HOWEVER, there is a context, if DS was playing soldiers, or cops and robbers then I think this is great for imaginative play, but if he started mimicking GTA type stuff or being very violent then I would step in. He does already do the whole "peow-peow" thing in nursery, he has to go pass armed guards to get onto nursery lol...they're going to be influenced, as he grows up I will contextualise it more and explain good guys vs bad guys and why his daddy does what he does, but in the mean time I don't think he's doing any harm playing daddy in the playground.
Like jd83 was saying about the difference in what guns do, I know it sounds silly but it's like knives, I don't let DS play with knives, he knows they're dangerous and I won't let him help me cut things up, but he knows his little one is good for food...if that makes sense? He would never try and hurt someone with a knife. They can learn the difference between good uses, and bad uses. I'm not sure if that's a good comparison or not lol, I understand a knife is a tool but a child will have no reason to be with a real gun, but I'm sure he will grow up to understand the good and bad sides to them, guns are not a new thing to childhood, lots of us grew up with action men etc.
My MIL was very anti guns, anti gun play, anti hunting, she's a big hippy lol....and 2 of her sons ended up as infantry soldiers in the military. Oh and her daughter is marrying the keenest hunter ever lol.