How Sylvester Stallone keeps those 'Rambo' kills fresh in 'Last Blood' after 5 films, 37 years

Nothing is ever over. At least not when you're Sylvester Stallone's John Rambo, who makes his fifth film appearance in 37 years with "Rambo: Last Blood."

Stallone, 73, has grayed and doesn't bare the impressive biceps he once wielded as the Vietnam veteran reluctantly compelled to kill again in 1982's "First Blood."

But one unwavering truth remains unchanged in the latest Stallone-penned incarnation: You're going to need a lot of body bags when the guerrilla war specialist is done.

"Last Blood" (in theaters Friday) finds Rambo pulled back to his lethal calling after a sex-trafficking Mexican drug cartel kidnaps his friend's beloved teenage daughter (Yvette Monreal).

Here's how the filmmakers keep the kills rolling after nearly four decades.

PSA: Rambo's 'hometown' of Bowie, Arizona, is celebrating Rambo Day

Stallone is back as John Rambo: Watch the trailer for 'Rambo: Last Blood'

Fans who like vengeful gore get plenty of it

"First Blood" famously saw one small-town lawman who beat Rambo take a spiked spring trap to the legs. The gore, and deaths, have been amplified throughout subsequent films. "Last Blood" includes an unflinching scene of a high-ballistic bullet to a foe's face.

"It's horrifying, but I don’t want to fake it," Stallone said at a news conference last week. "When it’s a Rambo film, they expect to be uncomfortable when it gets to the killing fields."

Nothing is deemed too gory. Director Adrian Grunberg recalls one scene where Rambo sprays bullets into cartel combatants already dying in pain. The moment was temporarily cut.

"And then it was like, 'Rambo hates them. He wants to spit on their graves,' " Grunberg tells USA TODAY. "So we put that back in."

Everyone pitches in with devising creative havoc

The body count in the climatic final battle quickly tallies double digits, so Stallone encouraged every film department to come up with imaginative ways to dispatch foes. The prop master devised a handmade bomb detonator to dispatch speeding SUVs driving into Rambo's ranch (prominently displayed in the trailer).

"But no one knows Rambo like Sylvester Stallone," says Grunberg, who says most of the creative ideas come from the star himself.

The explosions play a familiar role in the "Rambo" franchise.

"It’s not that we implement explosions because it’s what people expect, but it’s in the character's nature," says Grunberg. "Rambo has this knowledge, so it comes about naturally when building these scenes."

Rambo loses the headband, keeps the knife

Stallone is in terrific shape with an enviable head of salt-and-pepper hair. But a decade after the fourth "Rambo" movie, his famed character has lost the signature headband that held his big hair, going for a more age-appropriate, civilian style.

"There wasn't a big discussion about this. Rambo is in a different place in his life," Grunberg says.

Another concession to the passage of time is a lack of shirtless warrior shots, even if the buff poster suggests Stallone could pull it off.

Rambo still has his penchant for big knives, with his original survival knife on display in his tunnel hideout and newer blades brought into play. Likewise, he continues to use the trademark compound bow, first pulled in "First Blood."

The killing comes at a furious pace

Stallone learned the success of "First Blood" centered around slashing a bloated early cut to a lean 1 hour and 33 minutes. "Last Blood" follows a similar pattern of Rambo being done wrong and beaten by foes before seeking revenge – setting up the brutal traps for righteous retribution that flows with efficiency.

All of this is done in 100 minutes of "Last Blood" running time.

"That is definitely a Rambo trait. He takes a good amount of time creating his traps, and this world," says Grunberg. "But once the killing starts, it really moves."

This article originally appeared on USA TODAY: Rambo: Last Blood: How Sylvester Stallone keeps killing after 37 years