All I remember about the movie is two scenes, one is where they are in a ?jeep? trying to drive away from a worm underground but the road they are going through has mines so they end up being blown up. The other one is what I assume the ending, where the main character and a woman are inside a helicopter, but a worm pops out of nowhere and is about to eat the heli, this causes the main character to grab a grenade belt and jump in it's mouth. I watched this like 10 years ago and honestly don't even know if this is a real movie or a fever dream. Also, I think the movie was set somewhere in the desert.
This is Sand Serpents (2009).
Sand Serpents is 2009 Canadian made-for-television sci-fi action horror film directed by Jeff Renfroe. It is the 19th film of the Maneater film series and originally premiered on Syfy on July 11, 2009.
A small group of US Army Soldiers are stranded in the remote Afghan desert. But it ain't the Taliban that's worrying them, it's these giant refugees from Tremors. In fact the big worms prove to be an ally of sorts by doing better against the Taliban than themselves but battling these enemies is something not covered in their training.
As you can see towards the end of the video below, there is a scene where a man sacrifices himself by leaping into a giant worm's mouth from a helicopter, in order to blow the worm up so the helicopter can escape.