[Robert]

Can underbarrel weapons be modified?

Assume I have a Yamaha raiden with underbarrel shotgun and underbarrel grenade launcher.
A ) Can I add e.g. personalized grip or barrel extension to those two underbarrel weapons?
B ) Can I add an underbarrel weapon mount modification to the underbarrel shotgun?
C ) What happens if I add e.g. personalized grip to the Yamaha raiden, do the two underbarrel weapons gain the AR bonus?
D ) Is all of that true if I add he underbarrel weapon mount modification to some other rifle which does not come with factory fitted underbarrel weapons?
E ) What happens if I add e.g. personalized grip (firearms) to a rifle which has underbarrel chainsaw added? Does that one also gain bonus?

Thanks for the clarification.

[Stainless Steel Devil Rat]

Can underbarrel weapons be modified?

Note that underbarrel weapons are themselves a modification and not a weapon per se.  Modifications are never said to in turn have their own modification slots. Ergo, no underbarrel weapons on your underbarrel weapons and etc.

That answer should apply to all your successive questions, but I'll give some thoughts on each in turn:

Assume I have a Yamaha raiden with underbarrel shotgun and underbarrel grenade launcher.

First of all, I do believe that the Yamaha Raiden does not have two underbarrel weapons but one...  One underbarrel weapon that's able to fire either shotgun shells or grenades, whichever you happen to load into it.

A ) Can I add e.g. personalized grip or barrel extension to those two underbarrel weapons?

Nope.  It not only doesn't make any logical sense (underbarrel weapons have no grips!) they don't have mod slots anyway.
Personal view caveat: An underbarrel weapon probably should benefit from most modifications you may have on the entire weapon.  For example, you can't put a personalized grip on the underbarrel shotgun/GL, but you CAN put a personalized grip on the Raiden and both weapons would benefit.  IMO, not a formal ruling!

B ) Can I add an underbarrel weapon mount modification to the underbarrel shotgun?

I think you know that's a silly question.  But if not: No.  Hard no.

C ) What happens if I add e.g. personalized grip to the Yamaha raiden, [does the one] underbarrel weapon gain the AR bonus?

It's technically unclear, with room to legitimately say either "Yes" or "No".  But it's more fun to say "Yes" instead of "No".

D ) Is all of that true if I add he underbarrel weapon mount modification to some other rifle which does not come with factory fitted underbarrel weapons?

It's easier to say "No" in this case, but it's probably still better practice to still say "Yes".  If you say "No" in either case, you have to delineate which, if any, mods for the weapon do not extend bonuses to the underbarrel weapon.  If the personalized grip won't give benefit, then what about smartgun?  etc.  Again, I view it as being both more fun AND more easy to just say "Yes".

E ) What happens if I add e.g. personalized grip (firearms) to a rifle which has underbarrel chainsaw added? Does that one also gain bonus?

I don't think there are two kinds of personalized grips... a personalized grip just gives a different AR bonus dependent on whether the weapon is a firearm or a close combat weapon.  So you don't put a firearms personalized grip on such a weapon.. you just put a personalized grip on it!  And of course when employed as a firearm you get one AR bonus, and when employed as a close combat weapon you get the other AR bonus.

[Robert]

Thank you for the clarification!

A ) I agree to all statements, but I am massivly confused by the statement that Yamaha Raiden has only one underbarrel weapon which can fire either grenades OR shotgun ammunition. This is definitively not the way I understood the rules. Main reason is that the two weapons have different ammunition number and loading, the shotgun has 2 shots "break loading" and the grenade launcher has 4 shots in a "clip". They also have different firing modes (grenade launcher only Single Shot, shotgun also Semi Auto). In German translation it also clearly states "Granatwerfer sowie Schrotflinte" which means "grenade launcher and shotgun" (whereas the US original just states "shotgun/grenade launcher" which is more open to interpretation.)

B ) Assuming now we want to add the benefits of modifications done to the main weapon to the underbarrel weapon as well, that would surely not apply to ALL modifications (e.g. an improved gas vent or longer barrel on the main weapon should not impact the underbarrel weapon). What do you think of the list below?

• NO means "do not apply benefit to the underbarrel weapon"
• YES means "do apply benefit to underbarrel weapon"

- Accessory Rail NO
- Barrel Extension NO
- Biometric Gun Lock YES
- Collapsible Stock YES
- Custom Style YES
- Easy Breakdown YES
- Folding Stock YES
- Foregrip YES
- Gas Vent (improved) NO
- Gecko Grip YES
- Heavy Weight YES
- Light Weight YES
- Melee Hardening YES
- Metahuman Adaptation YES
- Nanoconstruction YES
- No Stock YES
- Personalized Grip YES (underbarrel ranged weapons get +1/+1 and underbarrel melee weapons get +2 / 0)
- rEVOlution Arms Collapsible Stock YES
- Rigid Stock YES
- Ruthenium Coating YES
- Safe Firing IFF System YES
- Short Barrel NO
- Side Ammo Mount NO
- Stock YES
- Trigger Removal YES
- Underbarrel Weapon Mount NO
- Underbarrel Weight YES
- Weapon Commlink YES
- Weapoin Security System YES

And while we are on that topic can I apply melee arms modifications to an underbarrel melee arm (currently only the Praetorian blade and underbarrel chainsaw)?
- Dikote
- Smart Materials
- Flashing Blade
- Glowcoat

Can I add club melee modifications to firearms with melee hardening?
- Spikes
- Zapper Coating

I do hope the answer is always NO to the melee mods, however wanted to ask. 

To close out the topic completely, I assume underbarrel weapons benefit from some accessories as well:
- Airburst
- Bipod
- Eagle eye
- Gyro mount (base and II)
- Hip pad bracing system
- Laser sight
- Scope
- Shock pad
- Smartlink
- Tripod

Thanks!

[Stainless Steel Devil Rat]

Raiden has 1 dual purpose under-barrel weapon, or 2 different underbarrel weapons:

As I said, I *think* it's 1 dual purpose weapon rather than 2 distinct weapons.  The Colt M-23 establishes that it's possible to have an exception to the "you can only have 1 under-barrel weapon" rule.  So go with whichever is more fun for your table.  I happen to prefer making "shotgun or grenade launcher?" a choice that has to be made ahead of time by which ammo  you loaded.  But allowing BOTH kinds of ammo to be loaded, and using it as a shotgun and as a grenade launcher on alternating combat rounds is more permissive.  So you do you!


Your proposed list of what is and is not compatible with underbarrel weapons:

I'll be honest.  I didn't parse it closely or look for things like "can you even add that mod after your underbarrel slot is already occupied?"  With that being said: If you like your list, by all means go with it! SR6 is supposed to rely on GM discretion, not spell every little thing out for them!