[Michael Chandra]

Yes.

Hm, good point, wonder why they say you can turn machine guns into miniguns when there's no rule for it. Now the High Velocity mod takes a LOT of effort and costs twice as much as the gun, so a Minigun variety would be at least that much. Hm, I'd call the Vindicator overpriced if all it takes is a x3, but the Ares MP-LMGx3 might be cheaper but would be stuck with a gas-vent 2 that you would want to get rid of in many cases.

[Aryeonos]

Why on earth would you remove the gas vent? Just upgrade and it overwrites, at any rate, the rule is the machine gun can be a minigun, when it is built.

If we paint the barrels red, do they spin faster to get more bullets out? 

It'll only shoot as fast as it is snazzy, you'd want to paint it blue so the shots are luckier, and thus land more. Maybe even set up an airbrush in front of the belt feed to make sure each shell is yellow.

[Michael Chandra]

You can't remove installed gas-vents and can't equip guns that have one with another one, according to SR4a.

[Aryeonos]

I believe you'd follow the rules for removing upgrades, or stock upgrades, then add in the better version of the upgrade. Either that, or pick a different gun to have as an electric driven gatling gun. (Or gas driven gatling gun.)

[Michael Chandra]

See, that's the idea. The thing has an annoying gasvent2 so would be impossible to get a gasvent3 on, so for that one recoil you'd pick another gun which you pay more for. So the Vindicator isn't too expensive in comparison because it doesn't burden you with an inferior gasvent.

[mtfeeney = Baron]

It doesn't say you can't upgrade.  It says you can't add a gas-vent system on top of another gas-vent system, pretending that they stacks since the first is stock.  Or, to be more precise, it says:

"Weapons already equipped with a built-in gas-vent system cannot be equipped with an additional gas-vent system."

[Michael Chandra]

Are there rules for upgrading existing modifications though?

[mtfeeney = Baron]

Yes, in Arsenal.  p.129, I think.

[Michael Chandra]

Just talks about removing. Add to that that Gas-vents actively state they cannot be removed.

[Mantis]

Michael,  only the gas vent accessory cannot be removed once installed (pg 322 SR4A). The mod has no such restriction and since all such things that come pre-installed on a weapon count as mods, you can just yank it out and replace it with a better system. (pg 152 Arsenal)

mtfeeney, the mini-gun rule, if you haven't already found it, is on pg 30 of Arsenal. Basically, mini-guns fire up to 15 rounds in FA mode with all that entails (recoil, damage bump, dodge mod).

[mtfeeney = Baron]

Hmm, so if it comes with gas-vent 2, you have to put gas-vent 3 on through modification and not as an accessory. 

[Michael Chandra]

That sounds horribly iffy, Mantis. So the one accessory that mentions it cannot be removed and that you can't add a second if it came with one can simply be removed as mod? I'm not really willing to buy that as explanation. If it were to actively mention it doesn't follow that rule, I'd go for it, but it's rather iffy to take the conclusion out of this absence.

[Mantis]

Well the modification rules do say you can remove any mod, even the ones that come stock on a weapon. Accessories also frequently follow slightly different rules than mods. Look at the silencer for example. The accessory gives a -4 to perception tests while the mod offers a -6. The sling accessory just makes it harder to drop the weapon while the mod offers concealability bonuses.
With the gas vent system I look at it this way. If I choose the accessory, I lose the barrel mount slot but none of my mod slots. If I choose the mod, I can keep the barrel mount accessory slot free but it uses up 2 of my mod slots. That is a pretty hefty price tag. The only things you are likely to use in the barrel mount accessory slot aside from gas vents is a silencer/suppressor or maybe a bayonet. There are all kinds of things you can use 2 mod slots for though, including other recoil systems. Having the accessory not removable balances that out and like I said, what else are you going to use the barrel mount for?
Keep in mind, in no way am I saying you can stack gas vent systems of any type. The rules are very specific on that one, but you can yank the gas vent mod, and only the mod, and replace it with a better system.

[mtfeeney = Baron]

Damn, I always assumed you can't get a barrel mod and a barrel accessory...  stupid, stupid, stupid me.

[Michael Chandra]

I'll give you RAW because they do not use a reference to SR4a and instead rehash most of it, but I'm not sure about RAI. Removing a gasvent that it comes with and replacing it with a cheap external superior one really makes the low-gasvent weapons plain silly, since it's no longer an actual limitation.

So, if we go with it RAW, that means if Minigunning a weapon is an extra +200%, the Vindicator is utterly inferior in price to the Ares MP-LMG. On the other hand, it already has minigun functionality. Brings us back to the question: Would treating Minigun modification as HighVelocity in costs/threshold/availability be fair?

mtfeeney: You can have both a Suppressor and a Gas Vent through mods, but can only have one turned on at a time. So having both barrel-mod and barrel-accessory is possible.