It says in the CC or the SR3 somewhere that the autocannon "fires stable high explosive rounds" or something to that effect. This leads to my question: If this is true what kind of "blast radius" would the rounds have. When you look at similar real life weapons they can technically "miss" but still maim/harm the target.

Any thoughts on how this can be addressed? In the game autocannon just appears to be a higher power MG with lower ammo capacity.

yeah, that's what it seems like to me, too. give it a blast radius of -3/m, offhand.

IIRC it fires panther canon ammo which has a 1m blast radii. that's it.

Since it doesn't have a blast radius I always figured they were a kind of HESH/HEAT round.

Where, oh where, is Raygun when you need him?

Basically, I've always assumed that assault cannons fire a 20mm round with an impressive fragmentation ability, just like explosive bullets. While I'm given to understand that you can fire a 20mm grenade, it won't have nearly the penetration of a straight round. If you're not giving a blast radius to explosive bullets, I wouldn't give one to assault cannon rounds.

And don't knock the autocannon. They can easily scale damage up to Naval levels when loaded with AV ammo. The ammo limitation doesn't apply when they're modified for belt-feed; and a full-auto spray from a [vehicle mounted] assault cannon is a nightmare for anyone not in a heavily armored vehicle-- and deadly even for them.

I wish I had more experience with explosive ammunition than I do. Once watching a 25mm Bushmaster punch away with HEI at a car hull from about 1,000 yards through 10x binoculars really doesn't help judge these things a whole lot. TheOneRonin probably has a better idea about that kind of thing than I do.

The intent of modern cannon rounds is to penetrate rather than fragment, so there's generally not a lot of material there to go flying all over and cause secondary wounding effects. Most 20mm+ explosive loads are shaped to penetrate vehicle armor with a jet of molten copper (and cause spalling), so the majority of the energy of the blast is directed forward. Still, there will be a blast radius, though how lethal it is to things not standing in front of it, I'm really not sure. I image that it could be relatively nasty within 5 meters or so, depending on the round. Though having to deal with staging down a D wound when standing within 5 meters from impact doesn't really sound right to me. Though I'm pretty sure that the concussion alone would be enough to deafen if you were standing within 10 meters or so.

If you consider .50-cal rifles Assault Cannons, the blast radius of explosive ammunition is pretty unlikely to be lethal beyond a couple of feet. The bigger the round, the bigger the boom, the bigger the blast radius.

In another thread, I suggested dedicated HE shells for Assault Cannons doing 8S, -1/m. The problem with using the canon Damage Code and a Blast is exactly what Raygun said: Having to stage down D is just too much. On the other hand, if you're actually hit by a 20mm HE (any type) round, 8S is too little.

I decided 8S, -1/m for a dedicated HE round, because then it's basically a slightly smaller mini-grenade. If you keep the Blast at a very low level, like -4/m or -5/m, then you could keep the Damage Code, I guess. That is, you can keep the DC anyway, but Assault/Auto Cannons will suddenly became a lot more bad-ass. Compare to the non-AV rockets and missiles, for example.

It shouldn't be too damaging, IMO. Heck, I could recover my sensors intact and reuse them after I use them to record the waveform readings from the impact and subsequent explosion of a 25mm cannon round.

I've spent a good bit of time around M2 Bradleys and their 25mm gun. As far as I can tell, that's about as close to a SR Assault Cannon/Autocannon as they come. Now, on to what I know.

Our Bradleys carried two types of ammo: AP and HE. The AP rounds is what we used against everything from Tanks to armored APCs. We only switched to HE for light (unarmored) vehicles and for fortified infantry positions. Not ever having been on the receiving end, I can't give you exact details, but I'm pretty sure that a single 25mm HE round isn't going to do much explosive damage beyond a meter or two, and the rest of the damage will come from shrapnel/fragments.

When it comes to SR mechanics, perhaps the best way to represent this is a separate damage code for blast radius. Aus has some good suggestions, but I still think an 8 Meter blast radius is a little high. I would lower it down to 4 meter max, and most likely only 2 meters.

The basic thing to keep in mind is what these weapons were designed for. Any cannon round (short of a naval gun) that is designed to blow up real big on impact isn't going to be the best armor penetrator. Likewise, a shaped-charge explosive round (which is most likely what the SR authors were thinking when they invented the PAC) or AP round is going to do a good number on vehicles, but isn't going to affect much outside of that. Any area affect damage is, at best, a secondary benefit.

If you really want to level a vehicle AND fubar stuff around it, might I suggest using a bomb. A really big bomb.