thats why the first stage isnt the rocket but the propellant that launches it from the barrel, the rocket propulsion engages after its left the barrel
"A launch motor using conventional rocket propellant ejects the missile from the launcher, but stops burning before the missile clears the tube. The flight motor is ignited only after a delay to allow for sufficient clearance from the operator." -http://en.wikipedia.org/wiki/FGM-148_Javelin#MissileFact is, the Bolter's construction doesn't have enough depth behind it to classify it using modern military terms. The words "acting like a miniature rocket" is to just give us idea of how the round is expelled. Even so, everything else about the Bolter fits the definition of a Rifle. It's compact, takes a magazine, and is a mid-range assault weapon.
Its a bolter round, in basic find a rifle that fires big ass rounds like the 0.50 calibre rounds for sniper rifles or something bigger, and then add a mix to it to see how it performs.
We've all read the books (presumably, maybe i dont know who cares), we all know that the bolt round is the single most opressive munition in the imperium of man. Not because of how it shoots or sounds, but because of what it represents. Dominion, and the ability to kill indescriminately. The sound is quoted as being "Terrible. So terrible that those who have heard it want nothing to do with war ever again." Of course that is heresy era rhetoric. There have since been contact with several races that enjoy the sound, such as Orks and their progeny.
View: http://www.youtube.com/watch?v=tnHyEhS1lSM sorry to spam, and not sure if I'll get into trouble linking away from the forums to youtube. I don't own this, but I'm pretty sure most of this chaps information is accurate. I found it on the interwebs after all
The Foolish loyalists see their weapons as instrument's of "the emperor's divine wrath", fools they are, for the bolter is but another tool, and only true power comes from the dark gods.
You can almost hear the modern day autogun from where that sound byte comes from. My suggestion would take something that makes a louder 'smack' noise, like a high velocity semi-auto rifle. And I really liked the bolter sounds in space marine. Except for the twin-bolter. It just sounded meh, to me. The bolter sound byte from the Ultramarines movie also felt like it gave it a good strong punch.