Robert Heinlein's 1959 novel "Starship Troopers" presents a futuristic war fought by heavily armored infantry, that when suited up, makes you look like a "big steel gorilla." Today, the U.S. Army and Marines are edging closer to the Mobile Infantry of Heinlein's world by reportedly taking an interest in armored face shields.

The Army hasn't made the shields part of its standard kit – not yet. But, according to Military Times, it has deployed thousands of them, and is looking to buy 160 more, with potentially 2,000 more shields to follow. The Marine Corps, meanwhile, is "keeping tabs on the Army's plan to test face shields," and is looking at "gear that will protect Marines' faces." Currently, individual Marines deployed to Afghanistan pay for face shields on their own – the Corps has so far not ponied up the money to field the shields.

Designed to protect turret gunners against explosive fragments, the shields are starting to find a role with infantrymen and are now advanced enough to stop rifle rounds. In a demonstration by Indiana-based manufacturer MTek (above), a 7.62mm round fired from an AKM variant impacts one of the company's FAST G3A shield, blowing it off a mannequin's head. (Before being blasted off, the shield was bolted onto the mannequin's helmet.) The shield's polyethylene armor stops the bullet, but looks painful. A bullet hitting a face shield can possibly break bones and knock out teeth. Though, consider the alternative.

"Don't get me wrong, it's going to hurt," said Gunnery Sgt. Ryan Bowser, a Marine reservist and business development manager for MTek. "It's going to hurt a lot, probably. But it's better than the other option. You get hit in the face with an AK round, it's probably not going to hurt because you're dead."

The video requires a little bit of explanation, too. The mask being flung off by the bullet is the "absolute worst case scenario," Bowser said. "The only way that effect would be exactly replicated on a person is if they were standing with their heels, their rear end, their back and head up against a wall," he added. And that's without the added weight of a 200-lb Marine (not including equipment) helping absorb the kinetic energy.

Fortunately, the likelihood of being hit in the face with a bullet is pretty slim in comparison to the massive threat posed by bomb fragments. Still, "guys are using them for everything," Bowser said. The shields are popular with members of the military's bomb squads, and the company has released a lighter and more compact model for dismounted soldiers and Marines, which helps get around the problem posed by larger face shields, namely disrupting the the wearer's ability to manipulate small arms.

But there's also questions over how much armor is too much. How much armor is necessary to save lives without cutting into Marines' speed and maneuverability? (MTek's latest shield weighs less than one pound – not a lot, unless it's hanging on your head.) How much armor is too much? At what point do troops keep behind the armor instead of moving forward to confront the enemy? Too much "turtling" behind body armor and giant blast-resistant trucks can also put distance between troops and the civilian populations they're supposed to protect.

Often, groups of heavily armed Marines can be intimidating to the locals. Want to make them more intimidating? Face shields.

Another problem is that the larger shields can block a soldier or Marine's cheek from his or her rifle stock, disrupting the ability to quickly acquire a sight picture. MTek's newer PREDATOR FAST G4 is shaped with this in mind, Bowser said, allowing a dismounted soldier or Marine to use his weapon more effectively than if he or she was wearing a bulkier version intended for vehicle-mounted troops.

"It can be done, but it's like any piece of equipment," he said. "It takes some time and practice to do that. Depending on what kind of suite you're using, what kind of suiting you're doing. You absolutely can put it on and engage with an M4 or an M16, or any of those things."

Perhaps the best news is the shield's potential to "mitigate some brain trauma sustained in bomb blasts," according to the Military Times. This is because the shield works to help absorb explosive blast waves, which can cause traumatic brain injuries that contribute to early dementia.

And if the Army makes face shields standard, and the Marines follow, that could be a sign the military might again dial up the armor. During the Iraq War, some up-armoring was necessary to protect against lethal bombs, but the military slowed the trend as it shifted to COIN – or counterinsurgency – doctrine that emphasized engagement with the civilian populace instead of riding around behind steel plates. And at some point, all this armoring gets kind of ridiculous.