Does the language of the soldiers in The Things They Carried sound “real”? Do the descriptions of the weapons have the feeling of reality?

The language of the soldiers does indeed sound real in the sense that one would expect this to be the kind of vernacular soldiers would use. The author indirectly tells us that the soldiers' words were full of bravado. Their language was enriched by expletives to hide their real fears. Their greatest fear was to be seen as cowards, so they used language that made them sound careless. They spoke in terms that were deliberately used to create the impression that they were unaffected by their circumstances. They wanted to give the impression that they were okay with what they had to do and with the conditions, risks, and burdens they were subjected to.

A few examples of these are:

Worms, Rat Kiley said. Right out of the grave. Fuckin' zombie.

Oh shit, Rat Kiley said, the guy's dead. The guy's dead, he kept saying, which seemed profound—the guy's dead.

Yeah, well, he finally said. I don't see no moral. There it Is, man. Fuck off.

The examples clearly illustrate a lack of intimacy. Death becomes a common reality and the men, instead of exhibiting sympathy or sorrow, present an uncaring, almost alienated attitude. Even Rat Kiley's repeated statement is an expression more of shock rather than sympathy. Although he knew the dead soldier, his reference is impersonal. He calls the deceased, Ted Lavender, "the guy," as if he is someone he doesn't know. The narrator states:

They used a hard vocabulary to contain the terrible softness. Greased they'd say. Offed, lit up, zapped while zipping. It wasn't cruelty, just stage presence. They were actors. When someone died, it wasn't quite dying, because in a curious way it seemed scripted, and because they had their lines mostly memorized, irony mixed with tragedy, and because they called it by other names, as if to encyst and destroy the reality of death itself.

In such an environment, language becomes a conduit through which the men can express their frustrations. The overuse of expletives symbolizes their anger, their fears, and everything else about their situation that they cannot really express openly lest they be dubbed cowards, unpatriotic, or even treacherous.

The weapons are described in finely accurate detail, which gives the descriptions a heightened reality. Their portrayal makes it obvious that the narrator knows what he is talking about, as in the following examples:

...a .45-caliber pistol that weighed 2.9 pounds fully loaded.

...the M-60, which weighed 23 pounds unloaded,...

...the standard M-16 gas-operated assault rifle. The weapon weighed 7.5 pounds unloaded, 8.2 pounds with its full 20-round magazine.

...the M-79 grenade launcher, 5.9 pounds unloaded, a reasonably light weapon except for the ammunition, which was heavy. A single round weighed 10 ounces. The typical load was 25 rounds.

It should be obvious that these are real weapons the speaker is describing and not some fake notion of what they should be like. He has seen and either used them himself or has seen them being deployed and is, therefore, familiar with their specifications.