If you examine a spectrogram of a typical LED, you'll see a high output spike of blue, then a dip at cyan rising to a high covering green through yellow, then tailing off through orange to a very weak red.
Filters are subtractive. A red filter will filter out colors other than red. It can't add red. So, if there is very little red there to start with, that's the best you're going to get - you can't convert some of the blue into red.
What some filters designed for LEDs do is allow some of the orange component through. That gives a brighter output, but as Moonshadow has noted, it results in a more orange tint, rather than a true red.
If you need the red to preserve your night vision, I would recommend a proper red filter, such as the Surefire F04 (which will fit most 1-inch bezel lights), or alternatively a light that has a red LED. If you will be using this light on military night exercises as you say, I think you'll find a bright light will be a handicap in more ways than one, and frowned on by your instructors. You don't need a bright light to help you read a map, and if you need to preserve your night vision you'll need a true red light, with no orange or other color component.