Size of an assault cannon Options

[Machiavelli]

Hey Folks,

long time no see and right away a question for you: does anybody know how big an assault cannon or an gauss-cannon is, especially in comparison to a heavy machine gun? I have no books at hand at the moment, maybe it is written down somewhere?

Thanks.

[NiL_FisK_Urd]

From a fluff perspective, it uses light tank gun rounds - i would place it in this size category: http://en.wikipedia.org/wiki/Category:Anti-tank_rifles

[Starmage21]

Hey Folks,

long time no see and right away a question for you: does anybody know how big an assault cannon or an gauss-cannon is, especially in comparison to a heavy machine gun? I have no books at hand at the moment, maybe it is written down somewhere?

Thanks.

The Assault Cannon that was featured in Robocop has always been the standard for what that thing looks like. They used a Barret M82 rifle with a prop imaging scope as the assault cannon in that movie. That said, I like the 20mm rifles that was suggested by NiL_FisK-Urd. They make much more sense, and could be fired from a rifle-like device not much bigger than the M82.

[_Pax._]

When asked this very question by newbie players, I reach out, I grab the nearest 12oz soda can, and I say "see this? This is the bullet an assault cannon fires. The bullet, not the case and propellant normally attached to it. Those are a bit bigger than another soda can. Starting to get the picture, now? (IMG:style_emoticons/default/smile.gif) "


Of course, in reality, a 20mm or 30mm Antimateriel Rifle is probably closer to what it'd actually be like. But for the purposes of a fairly cinematic RPG? Close enough.

[Nath]

I think the closest modern equivalent to SR assault canon is the Barrett XM109 "payload rifle" which fires 25mm explosive rounds. Oddly enough, it is actually shorter than a .50 M82 rifle (this review shows both side to side). I guess the 25mm round is so powerful that it does not need a barrel as long as a .50 rifle to be accurate. It's nonetheless slightly heavier, around 15kgs.

[Lionhearted]

Imagine a minigun where you replaced the cylinder with one big hunking barrel, that's an assault cannon!
Now for a gauss rifle... Are you familiar with the Tau?

[Starmage21]

I think the closest modern equivalent to SR assault canon is the Barrett XM109 "payload rifle" which fires 25mm explosive rounds. Oddly enough, it is actually shorter than a .50 M82 rifle (this review shows both side to side). I guess the 25mm round is so powerful that it does not need a barrel as long as a .50 rifle to be accurate. It's nonetheless slightly heavier, around 15kgs.

That thing is more of a mini-grenade launcher. Its not trying to do damage with kinetic force. Its about lobbing an explosive downrange.

[SpellBinder]

Imagine a minigun where you replaced the cylinder with one big hunking barrel, that's an assault cannon!
Now for a gauss rifle... Are you familiar with the Tau?

I think pathfinder rail rifles are a bit smaller than the Ares Thunderstruck, which I'd say is a bit smaller than the rail cannons the broadsides carry.

[Lionhearted]

Well bear in mind the Tau are quite short, a Tau rifle adapted to human size would be about right.

[Nath]

That thing is more of a mini-grenade launcher. Its not trying to do damage with kinetic force. Its about lobbing an explosive downrange.

Assault cannons were described as firing explosive rounds in the previous editions. The 4th and 20th Anniversary editions only mentions "ammunition common to the primary weapon in many small tanks" (though Gun Heaven also mentions explosive rounds). As far as I know, the 25x59mm HEAT and canister flechette ammunition have yet to be developed, but they would fit the bill.

[_Pax._]

I'm with Nath on this one. ACs in SR fire explosive rounds. They are VERY loud dakka. (IMG:style_emoticons/default/smile.gif)

[Lionhearted]

That thing doesn't resemble a Panther Cannon in the least.

[Starmage21]

Assault cannons were described as firing explosive rounds in the previous editions. The 4th and 20th Anniversary editions only mentions "ammunition common to the primary weapon in many small tanks" (though Gun Heaven also mentions explosive rounds). As far as I know, the 25x59mm HEAT and canister flechette ammunition have yet to be developed, but they would fit the bill.

20mm anti-tank rounds are exactly what theyre describing. They fly at ballistic speeds and hit with huge amounts of kinetic energy in addition to having explosive(or other) components.

That XM-109 does NOT do that. The projectiles are relatively slow.

[Nath]

20mm anti-tank rounds are exactly what theyre describing. They fly at ballistic speeds and hit with huge amounts of kinetic energy in addition to having explosive(or other) components.

That XM-109 does NOT do that. The projectiles are relatively slow.

Relatively. The M109 muzzle velocity is still above 400m/s. It's less than a sniper rifle (usually around 850m/s), and a lot less than an actual small tank gun (1,100m/s), and around the same speed than a pistol bullet.

They're not describing much actually: an assault cannon "fires shells equivalent to explosive bullets, but without the bullets inherent instability." "These highly stable explosive rounds are made of HDX superplast compound" (SR 3rd edition). It "fires stable superplast explosive warheads" (Cannon Companion), "special ammunition common to that used as the primary weapon in small tanks" "with tremendous recoil" (SR 4th edition), "large-caliber explosive rounds (Gun Heaven).

Past the "tremendous recoil", it never says anything on kinetic energy, and mostly focus and the explosive part. I see nothing inherently wrong as describing HEAT ammunitions as "common to that used as the primary weapon in small tanks," even if that ammo terminal velocity happens to be slower. Kinetic energy contributes little to zero to a HEAT effect. If the intent is to have a HEAT man-portable precision weapon, there's no point in increasing terminal velocity to the point that a man could no longer use it because of recoil (yes, I know, trolls have an easier time with assault cannons, but other metatypes can nonetheless use them). Obviously, we don't have the technology of SR. I just find it more likely to imagine that assault cannons are XM109 with some tweaks and possibly slightly faster ammo, than it is to imagine than they somehow managed to make a man-portable version of the M242 Bushmaster than can be fired with a mere bipod.

[Manunancy]

As was previously mentionned, I'd think they are lighter than heavy machinegun, on par with the anti-material riffles like today's Barret M-82 - think 30 lbs and five feet. A heavy machinegun is in the same length range but will weight from one and half to twice the wieght thanks to it's ability for autofire - and the heavy weight of a 100-round belt compared to a 5 to 10 round clip. When you're considering .50 and over ammo, it weights a lot.

Gauss riffle are probably about the same too - you save weight on the ammo (no propellant and casing) but add the energy storage and magnetic propulsion.

As far as assautl canon go, there's probably two main schools of design : either you use a relatively large bore, low velocity round which relies on a shaped charge to punch though armor and damage the target (probably somehting in the 25-30 mm range), or you go for a smaller and faster armor-piercing round which relies on kinetic energy to punch though and probably packs a small explosive or incendiary paylod to improve the damage behind the armor (probably in the 15-20mm range). The latter will be heavier, wih a stronger recoil but an increased range and accuracy.

[Umidori]

From the in-book illustrations of the Panther XXL, I always pictured assault cannons as being around the size of a man-portable rocket launcher. All the rifles mentioned in this thread are about the right length, but not nearly bulky and hefty enough in my mind.

That said, I did stat up a homebrew custom Panther XXS, a working miniature assault cannon replica that serves as a heavy pistol with boosted AP, but which requires custom handmade ammunition and can only hold one round at a time. Had some quality laughs tossing that into a game.

~Umi

[Machiavelli]

Ok, thank you very much. So the Assault Cannon or Gauss-Rifle wouldn´t be much bigger in the hands of a troll than a MMG or HMG? But now even more questions come up:

1) Do you think assault cannons and gauss-rifles are easily detachable?
2) How long would assembly take?
3) what skills do i need? I know that you need the armorer skill to re-adjust sniper-rifles, but simple breakdown for cleaning? Armorer skill? Come-on.
4) my GM says, that the gauss-rifle halves armor and then has an additional AP. Is that correct? Where is that mentioned? Didn´t find this section in the SR4A-book yesterday.

Thank you in advance.

[SpellBinder]

4) Well, it's not mentioned in the SR4a book as I don't believe there are any Gauss weapons in it at all. The Arsenal Errata v1.3.2 that is, as far as I know, floating around the internet, states this for the Ares Thunderstruck (should be easy enough to find via Google). The entry for the S-K Taurus Light Gauss Cannon (Arsenal, page 124) also states this in the text. Can't think of any other Gauss weapons at this time, but I'd expect they all have the 'half armor' modifier.

[Machiavelli]

Ah, this explains everything. The english errata are already included in german publishings. Thank you. Now we come to question 1-3. ^^

[_Pax._]

Ok, thank you very much. So the Assault Cannon or Gauss-Rifle wouldn´t be much bigger in the hands of a troll than a MMG or HMG? But now even more questions come up:

1) Do you think assault cannons and gauss-rifles are easily detachable?
2) How long would assembly take?
3) what skills do i need? I know that you need the armorer skill to re-adjust sniper-rifles, but simple breakdown for cleaning? Armorer skill? Come-on.
4) my GM says, that the gauss-rifle halves armor and then has an additional AP. Is that correct? Where is that mentioned? Didn´t find this section in the SR4A-book yesterday.

Thank you in advance.

1: Do you mean, disassembled ...? Strictly RAW, none of them are. You can however get the "Easy Breakdown" modification, using the rules for Weapon Modification found in Arsenal

2: If you have Easy Breakdown? 3 rounds for Manual breakdown, or 2 rounds for Powered Assist breakdown. If you don't? As long as your GM wants it to take, with a probable minimum of 4 complex actions, possible more.

3: If you have Easy Breakdown? No skill required; Tab A goes into Slot B and is held in place by Pin C, and you're done.

[Dakka Dakka]

1) Do you think assault cannons and gauss-rifles are easily detachable?
2) How long would assembly take?
3) what skills do i need? I know that you need the armorer skill to re-adjust sniper-rifles, but simple breakdown for cleaning? Armorer skill? Come-on.

You won't find those details in the books, because they don't go into that much detail, heck they didn't even get the distinction between a detachable (box) magazine and a clip right.
I'd say, they work like anti-materiel rifles, so they can also be field stripped like those weapons. The cool thing about assault cannons and other weapons is that their sights cannot be disturbed by combat. That rule only applies to sniper rifles.
Since there is no RAW for misfires and other malfunctions, ask your GM what you would need. Unless the character is unskilled, I'd simply say take a simple action to ready the weapon again. If the shooter has no clue, I'd increase the time to a complex action and require a LOG+Armorer (1) test.

[Lantzer]

It's this big:

http://robocop.wikia.com/wiki/Cobra_assault_cannon

When in doubt, go to the source material.

[StealthSigma]

From the in-book illustrations of the Panther XXL, I always pictured assault cannons as being around the size of a man-portable rocket launcher. All the rifles mentioned in this thread are about the right length, but not nearly bulky and hefty enough in my mind.

I've always thought of them as at least a stripped down 20mm anti-aircraft or anti-tank gun and potentially upwards of a stripped down 40mm.

http://en.wikipedia.org/wiki/Lahti_L-39

[Lionhearted]

Well the assault cannon in arsenal looks a lot like that.
But the panther XXL looks like a tube with a handle on it pretty much.

[StealthSigma]

It's this big:

http://robocop.wikia.com/wiki/Cobra_assault_cannon

When in doubt, go to the source material.

That is, unfortunately, an outdated source. That gun is a Barret M82 modified for the film and there's no reason to suspect that the Barret Model 121 in Arsenal is too much off in size. Assault Cannons must be larger and bulkier than that.