[WellsIDidIt]

I can see the point of making different calibers matter in certain genres that emphasize isolation and low resources, but Shadowrun doesn't make either of those a high point.

Personally in Shadowrun, I've actually cut down the number of ammo types to make things even simpler. I use the following list

Ammo Types -- Weapon Types that use it
Light Pistol -- Hold Out Pistols, Light Pistols, Machine Pistols
Heavy Pistol -- Heavy Pistol, SMG
Assault Rifle -- Assault Rifle, LMG
Sport Rifle -- Sport Rifle, Battle Rifle, MMG
Sniper Rifle -- Sniper Rifle, HMG

Unless the weapon specifies a different ammo type (such as the SMGs that fire AR rounds) I let ammo shift around like that. Specialty weapons use the same ammunition as normal like shotguns or assault cannons.

And IIRC, the Light pistol which can fire a Heavy pistol round is a revolver that can hold either a single Heavy Pistol round OR its capacity in Light Pistol ammunition.  So using it as an example to allow re-chambering to increase the damage of any weapon is ludicrous in the least.

The Multi-6 holds the same number of rounds either way, it just fires slower with heavy pistol ammunition (SS instead of SA). It's works essentially the same way as .38/.357 would.

[Aryeonos]

Only, have you seen that cylinder assembly? It's like something out of a spanish museum.

[MadBear]

On the .38/.357? No, but I do think This http://en.wikipedia.org/wiki/Automatic_revolver has a pretty interesting cylinder assembly.

I don't think there is much reason to increase the DV on an SMG to match that of an Assault Rifle. Assault riffles just have so much more room for accessories. Yes, they do have greater concealabity, which is about the only advantage an SMG has over ARs. If you really wanted to be nasty, you could re-chamber one up for High Powered rounds. There is nothing to stop you from doing that, it's in the rules, and if you wanted to go through the expense and trouble, go ahead. And risk getting caught. A good GM will use that to regulate offensively powerful weapons. Yes, even for my hand cannon.
What I was suggesting was a bit more moderate. +1 DV with reduced ammo capacity and increased recoil. And yes, it would allow you then load higher caliber Ex rounds too... just don't get caught with that gun. At that point it's not much different than HP rounds.
To me, at least, it's not always about min/maxing the best DV for a gun. It's about what your  character wants, likes, has wet dreams about.  So while re-chambering my BFG Ruger to take HP rounds would give me some serious stats(8P DV with -3 AP), the idea of just carrying around a Ruger that's holds higher caliber rounds(5 cy instead of 6 cy) has a lot more appeal.

So the next question is, if a gun IS re-chambered to take HP rounds, is that ALL it can take? Or could you load Flechette or SnS rounds too? The gun in question has the Ammo Select mod, and usually carries two or three types of rounds.

[Aryeonos]

Which one, the Mateba or the Webley? Either way, you stumbled upon my favourite revolvers, so I do have to kill you now.

[Mantis]

MadBear, as far as I know rechambering for high power rounds means you can no longer use any of the other types of special ammo. Rules are on pg 156 of WAR!.

[MadBear]

Oh, yup, there it is. Missed that part. Damn. I think I prefer the flexibility of APDS, Flechette, and SnS in the cylinder.

I do then have to ask about this: 'High-power rounds infict a –2 dice pool penalty when  red due to excess recoil.'   So, does that mean recoil is doubled? At first it appears that the -2 is applied to EVERY shot, including the first, which makes no sense. But then, if it was meant to be applied to each round after the first, then why not simply double uncompensated recoil like with Heavy Weapons? Or does HP recoil increase at a rate of -2 dice per shot instead of -1, and recoil still functions normally(ie Custom Grip removes 1 pt of penalty, Gasvent II removes 2 pt of penalty, etc)? In the latter case, a Heavy Pistol with a Custom Grip would suffer no penalty on the first shot, but would suffer a net -1 on the second(-2 for second HP round, Custom Grip removes 1 pt of penalty)?

[Mirikon]

High-powered rounds inflict a flat -2 every time you pull the trigger. In SS, that's a -2. In SA, that's -2 on the first, -3 on the second. In BF, that's -4 on the first, -7 on the second (recoil being cumulative, afterall), and so on. Oh, and because it is a gray area, it is GM's call whether recoil compensation helps to eliminate that -2 penalty or not.

[Shaidar]

Basically from a bigger boom than the weapon's frame was designed to handle.  Basically, how a .44 Magnum has a bigger kick than a .45ACP.

[Mäx]

As a former military weapon smith I can tell you that re-chambering a weapon is a real PITA.

Now, there are kits available IRL to reduce the caliber of a weapon, mostly these include a new magazine, barrel and some other parts along with instructions.  They take a few hours to install and don't much make for a better weapon.  The U.S. Navy used M1911s re-chambered from .45ACP to .22 to give new recruits a general feel for firearms.

However, increasing the caliber is more problematic than buying a new firearm that already uses the desired caliber.  I personally wouldn't trust a shadowsmith to handle the engineering necessary to handle the stresses involved with a larger round.

You can get AR-15 uppers in wide range of calibers and swapping one in doesn't take much work at all as far as i know.

[MadBear]

I understand and completely agree with the reasoning for the -2 recoil, but not for the first shot. That makes no sense at all. If you've not even pulled the trigger yet, how could the gun move, buck, kick-back, etc? Once you've fired the first shot, THEN there should be a recoil penalty. Unless the reasoning is that the extra force of the high powered charge shifts the barrel as the bullet is still traveling down it...

[Mirikon]

The reason for the extra penalty is because the round has more kick than a weapon that size normally has, which makes it harder to keep on target.

[CanRay]

The reason for the extra penalty is because the round has more kick than a weapon that size normally has, which makes it harder to keep on target.

Marlboro:  "You know, that gun costs about two dollars every time you fire it. That's two bucks a bullet."
Harley Davidson:  "Well how many'd I hit?"
Marlboro:  "You spent twelve dollars and didn't hit a goddamn thing. I nailed one and it cost about four and a quarter."

[Mantis]

MadBear, don't apply the recoil to the first shot, just as you would for any gun. Recoil before you have shot at all makes zero sense. Apply the penalty for all subsequent shots fired as normal. In a pistol or other SA weapon this means your second shot suffers a -2 uncompensated penalty (comp should work as normal and nothing in the description leads me to think otherwise). 
How you want to interpret that recoil for BF and FA is up to you though. The wording could be essentially that it doubles recoil or it could be the way Mirikon says it does. You can always play test it and see which way you like better.

[RHat]

The rule is that it applies to the first shot.  It is unclear whether or not RAW is that the penalty is recoil or not.  If you judge that applying on the first shot is inconsistent with being recoil, then you need to rule that the penalty is not recoil.

[Aryeonos]

I was always under the conception that the -2 was not recoil but just a -2 period. So a smartlink would override it, but a muzzle break wouldn't. I don't think it'd be too broken either way, but that's just the impression I got from the text. I have no idea how you would get the idea that it DOUBLEs recoil though.