Grenade Launcher Deviation

[kato13]

kcdusk 12-01-2005, 10:38 PM Do direct-fire GL 's have any deviation? I understand that indirect fire GL's have deviation and am comfortable with that. But I just fired a GL at 8 soldiers and missed. Where did the round go? With indirect fire it still might land close enough to do some damage, but what about direct fire?


I thought I'd use the indirect fire deviation method for now, look up a better answer later. My target was 60m away and the round landed (using indirect fire deviation rules) 40m to their right. Geese, did the GL go off accidentally or something?

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Targan 12-01-2005, 11:32 PM I use a d6 scatter dice (with arrow markings) to determine any kind of deviation, but the distance for direct fire scatter will be greater in-line with the target than to either side. All direct fired rounds (high or low velocity) tend to fall short rather than go long as a general rule (espicially with novice shooters), but having said that unless the sighted target was at or near ground level, the round will nearly always go past the target.


If the to-hit roll was a "critical failure" and the GM determines that the round went high, indirect fire scatter rules could be used, but otherwise the round will probably land somewhere between afew tens of metres short of the target and the extreme range of the weapon, and within an arc of afew tens of degrees to either side.


With a GL, the round will usually have a minimum arming distance. For non-HE high velocity rounds which fall short, the round may skip along the ground and still hit the target (I have done this myself firing 7.62mmN from an FN-FAL battle rifle).

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kcdusk 12-01-2005, 11:36 PM Some good logic there re direct fire likely being too short or too long rather than side to side.


Doesnt help me though! I am 60m away and it fell 40m short (shite, i might be in my own burst range!). LOL

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Targan 12-01-2005, 11:39 PM I take it the GL is an M-203/M-79/HK-GL? I dunno if the round would arm itself inside 20m. Sounds like the round was faulty, maybe old or affected by moisture.

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ReHerakhte 12-02-2005, 03:03 AM G'Day all,

Something else to consider with the low velocity 40mm rounds, they travel at about 76m/second, this is so slow you can actually see the round travel to the target area and a lot of fire correction is done by the operator observing the round in flight and then correcting their aim based on where they think it will land. If you're firing on targets from 300-400m away with an M79 or M203 and you're pretty slick, you can get the second round into the air by the time the first round is about to impact. A good operator, with some preparation (i.e. having the ammo very readily accessible), can pull off limited barrage fire.

By the way, you want to watch out for the M79, those bitches bite if you don't watch your trigger hand placement (the safety switch is located on the top of the weapon, just behind the breech - right near where the web between thumb and finger sits if you grip the weapon in the normal manner i.e. the way your trigger hand would grip a rifle without a pistolgrip) - I learnt the hard way but I only needed one lesson! You could tell those who had live fired the M79 and been biten because they kept their thumb on the same side as their fingers.


One other unfortunate consequence of the rounds' slow movement is that it can be affected by strong winds and also by foilage. Strong winds will make it deviate to the left or right (obviously based on wind direction).

And depending on how in depth your group wants to go, low velocity 40mm rounds typically have a real world lethal radius of 5 metres. They pack far less explosive than the fragmentation hand grenade and thus should not be given the same game stats but about half to one third of the Blast & Concussion values that the frag hand grenade gets (typical real world lethal radius for a hand grenade is about 10-15 metres).

So if it does come back towards you, keep at least 6 metres away and you should be safe from any lethal fragments!

There are some later developments of the 40mm that increase this lethal radius but they aren't likely to be available for the Twilight setting.


Cheers,

Kevin

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ReHerakhte 12-02-2005, 03:16 AM Something else I forgot to mention...

In regards to arming distance of the low velocity 40mm ammo, many of them require between 14 and 30 metres depending on the type, (although they all require centrifugal force to arm them they have different detonation requirements and therefore require different fuses).

However, the US designed M381 HE round has a large fuse that only needs to travel 3 metres to have spun enough times to arm it. According to the blurb in Kevin Dockery's "Compendium Of Modern Firearms", this makes the round "... useful for house-to-house combat where it can be fired around a corner into a room and detonate when it hits the far wall."


Just one more thing to make your Players nervous...


Cheers,

Kevin

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Targan 12-02-2005, 03:26 AM Once in my campaign ("one time at band camp!") Po was engaging in some room clearing and a small arms round punctured a WP grenade on his webbing, not causing it to explode but resulting in fragments of WP spraying out and onto him. He had a bandoleer of 40mm GL grenades hanging off him at the time, and it was funny watching Po's player freak has he made the rolls required to get the bandoleer off and throw it before any of the grenades cooked off. He managed to put a couple of walls and 90 degree corners between himself and the bandoleer before it went up, but he and another PC suffered punctured ear drums and couldn't use their radios for a while afterwards. They roleplayed it well, yelling at each other in RL as we played out the rest of the session. Po had his M-4's butt stock collapsed and the weapon was attached to his shoulder with a speed sling, luckily, because a regular sling probably would have been sitting on top of the bandoleer when he tried to extricate himself from it.

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