Surrealone

It is highly improbable that the full barrel recoil system was put on the GM6 Lynx platform due to the impracticality of a muzzle brake on a bullpup weapon.  Why?  Because the GM6 Lynx platform in that video had a muzzle brake on it... and I sincerely doubt anyone put that recoil system on the platform due to a muzzle brake being a problem ... and then slapped a muzzle brake on it, anyway.  But hey, it's possible ... just not very probable.
 
.50BMG small arms absolutely have practical military uses ... but man-shoulderable, man-fireable .50 BMG's with goofy full barrel recoil systems to render them man-shoulderable and man-fireable probably don't.  i.e. The ones the military fields are all intended to be shot from a supported position, not a standing, shouldered/unsupported position.

Wrong.  I give you the M&P 15-22 Integral ... by Innovative Arms: https://www.innovativearms.com/portfolio/iasw-integral/ 
 
The loudest sound this rifle makes is the sound of the action cycling (which is what you're hearing in this video).  For comparison, each cycle of the action makes about the same amount of noise a compound bow makes when releasing an arrow -- making it as silent as a bow and/or crossbow ... and probably a LOT quieter than that WWII commando crossbow when you consider the noise and time of re-cocking it (since the full cycle of the M&P 15-22 entails re-charging the weapon).

 
Yes, it is that quiet ... with standard or even high velocity ammunition, no less -- due to the barrel porting that's covered by the suppressor.  (At the range I've been asked if mine was a pellet gun!)

Oh I'm sure they'll come up with pintle mounts and pop-up, rotating turret mounts (for use in, say, the roof of an SUV) for it ... as there's really no market for the gun without accessories that make it versatile.

It apparently has options for 10" and 16" barrels, should longer barrels be desired.

Arch,
Take a gander at Damage Over Time...

GM's call as to what happens when stunned on a mount, as it's very situational.  In the given situation, I'd expect the rider to remain mounted unless the horse did something that might cause the rider to fall -- in which case, I'd offer no Ride roll or Dex check to preclude a fall if the character was still stunned when the horse did whatever it did.

​Just when I thought pocket guns couldn't get any uglier ... someone creates that thing ^^^^^^^^

This is typically caliber-dependent.  A high-power rifle (e.g. .308 aka 7.62 NATO) will produce ~167dB unsuppressed (and even louder with a muzzle brake installed).

Per OSHA, sounds louder than 85 dBA may cause damage if you listen for 8 hours or more. For every 5 dB increase in loudness (i.e. for every doubling in loudness), the amount of time you can be 'safely' exposed unprotected is decreased by half. For example, at 95 dBA, you can safely listen for two hours before damaging your hearing.
 
With that in mind, you can 'safely' listen to 115dBA continuously for 7.5 minutes; 120 dBA continuously for 3.75 minutes; 125 dBA continuously for 1.875 minutes; 130 dBA continuously for just under 1 minute (0.9375 min, to be precise); 135 dBA continuously for a bit less than half a minute (0.46875 min, to be precise), and 140 dBA continuously for a bit less than a quarter minute (0.234375 min, to be precise) assuming you don't encounter pain at 140 dBA.  
 
Keep in mind the OSHA 85dBA is relatively conservative ... and that despite this, people with more sensitive hearing will, of course, experience hearing damage at lower thresholds than those with less sensitive hearing.
 
The split-second impulse of a firearm at 140 dBA just isn't as audible or damaging as you suggest. Assuming there's no accompanying supersonic crack (due to use of subsonic ammunition ... or a ported barrel as on the Innovative Arms M&P 15-22 Integral for which I previously provided a youtube video) ... the impulse sound from the firearm will be easily drowned out in a wooded rural environment by highway or gravel road noise, jet engines roaring overhead at 30,000 ft (audible on the ground), the sound of birds/animals, and other normal daytime sounds/activities coupled with the noise-buffering effects of woodlands -- unless you're talking early morning rural stillness/quiet across open plains before even animals tend to be highly active.  In a bustling city like NYC or LA ... you'd probably not even notice a partial-second 140 dBA impulse during the daytime ... or even several of them. (To be fair, you likely also wouldn't notice several 150 or 155 dBA sounds, either ... due to sirens, car horns, yadda yadda.)
 
Here are some common noise levels -- the most damaging of which are problematic largely due to their continuous nature ... meaning long exposure times in most cases.  For proper context, a jet engine is listed at 140 dBA ... but its noise lasts a LOT longer than a firearm impulse and thus, it's generally considered unsafe if unprotected ... while a suppressed firearm impulse is only momentary at 140 dBA and is therefore, generally considered safe if unprotected.
 
Painful
150 dBP = fireworks at 3 feet (impulse noise)
140 dBP = suppressed high-caliber firearm (impulse noise)
140 dBA = jet engine
130 dBA = jackhammer
120 dBA = jet plane takeoff, siren
Extremely Loud
110 dBA = maximum output of some MP3 players, model airplane, chain saw
106 dBA = gas lawn mower, snowblower
100 dBA = hand drill, pneumatic drill
90 dBA = subway, passing motorcycle
Very Loud
80–90 dBA = blow-dryer, kitchen blender, food processor 
Loud (safe for 24 hours or more)
70 dB = busy traffic, vacuum cleaner, alarm clock
Moderate (safe for 24 hours or more)
60 dBA = typical conversation, dishwasher, clothes dryer
50 dBA = moderate rainfall
40 dBA = quiet room
Faint (safe for 24 hours or more)
30 dB = whisper, quiet library

This was precisely my point.  Also Christopher seems to imply I claimed the gun was silent when what I actually said was:
"For comparison, each cycle of the action makes about the same amount of noise a compound bow makes when releasing an arrow -- making it as silent as a bow and/or crossbow ... and probably a LOT quieter than that WWII commando crossbow when you consider the noise and time of re-cocking it (since the full cycle of the M&P 15-22 entails re-charging the weapon)."
 
Apparently he can't be bothered to read ... or he just doesn't remember what he reads.

Neither is a bow or a crossbow -- the latter of which is what was put forth by you as a an alternative to guns because guns aren't silent.
 
i.e. You're being a bit disingenuous (and apparently arguing for the sake of arguing) to call out the technical lack of silence on the gun unless you also do so for the non-silent alternative you proposed.  (i.e. To avoid implying the crossbow was completely silent.)
 
Note that contextually the gun only needs to be as silent as the alternative you proposed to render the proposed alternative moot.  In today's day and age -- there ARE guns that are quiet enough to do that.  Now comparing WWII guns to the proposed WWII crossbow alternative -- that's a different story. (But you didn't limit it to just WWII guns not being silent -- something which, when pointed out, is a form of me arguing for the sake of arguing, heh!)

Hey, I think you identified a niche for the pistol that I wasn't aware of.  Thanks for that.  Sadly, though, I see that niche as bass ackwards -- but I'm probably biased.

Here's another solution in search of a problem in the real world... but something potentially cool for gaming use.
 
 

Today I bring you the latest F*ck You to the BATFE from FightLite Industries: the FightLite RAIDER. 
 
Practically useless in every defensive scenario I can think of, this little 7.5" barreled blaster comes in either 5.56 NATO or .300 BLK, with the latter being the obvious choice given the short barrel length.  Screw on a suppressor, slap in a 20 round magazine of .300 BLK, attach a sling to the QD port on the end of the grip (so it can be easily hung/concealed under a duster, trenchcoat, or the like), and your mooks will be the silent but deadly life of your heroic opposition's party.

Okay, let me take a stab at this.
 
These are my assumptions of what is written.
 
First to define Combined attack we should look at what it won't let you do.
It won't let you Combine powers in a Multipower or VPP over the Pool cost You can only use up to the Total Pool points in any give Phase You could use two Variable slots up to the total pool points if you chose This is important since many characters tend to buy all of there offensive attacks in a Multipower. It won't let you make two HTH attacks using Strength for both (that would be a Multiple Attack) You could combine a Punch with a Hand Attack but if you had two weapons you couldn't use each of them as a combined attack since you would be using Strength twice and that would be a Multiple Attack You could do a Punch and fire an Energy Blast at the same time though, paying END for each It won't let you fire the same attack twice (as evidenced with Strength above) It won't let you fire at multiple targets However, it will let you shoot two AoE attacks at the same hex Firing at multiple targets requires Multiple Attack You can't combine Combat Maneuvers (this would also be Multiple Attack) You couldn't do a HTH Grab and a Strike as a Combined attack (this would be using Strength twice) So then what is a Combined attack for?
If your character had two powers that he paid for independently he could use both of them at the same time For example, Flare has an Energy Blast and a Flash attack which were bought independently she could use them both in the same phase at the same target If Neutron had a Telekinetic attack and an Energy Blast (bought separately) he could both Grab the target and shoot at him in the same Phase It should be noted that the target will not suffer the DCV penalties against the EB since he actually hasn't been grabbed yet (until the successful to hit roll) If your character wanted to Combine a Multipower attack with a power that wasn't in the Multipower he could do that as a Combined attack Flare has several Energy blasts (bought as fixed slots) in a Multipower and a Flash attack bought independently She could fire attacks up to the total of the Multipower pool and the Flash as a combined attack Some notes on using Combined Attack
As I mentioned previously the effects of one attack do not take place before the other This means that if your character has a PD drain and you use it as a Combined attack with a punch it doesn't drain the PD before the damage of the punch The effects take place at the same time so one does not get the benefit of the other So what is the difference with the Linked Limitation?
With Linked you Have to use the other attack You cannot use the Linked power independently (that is the Limitation) For example in the case above with Flare If her Flash attack was linked to an Energy Blast she couldn't fire the Flash by itself, she must fire the Energy Blast as well Cinematically, this represents a character using two attacks at the same time.  It might be two different Energy Blasts or Flash and an Energy Blast or Telekinesis or whatever.  It is done all the time in movies and TV Shows.  Think of an Energy Blaster using both hands to attack a target.  That could be two different attacks (if it is the same attack twice then that is Multiple Attack).
 
I hope this clears things up a bit.  Again, I am no authority on the game but this is how I view the rule.
 
Deadman
 
 

It also doesn't seem fair to downvote just because you disagree with someone … or because you feel offended by something someone wrote when that wasn't the person's intent.  The fact that this was done, suggests fairness isn't part of the equation that was used by some people when conducting their downvotes. Thus, it seems a bit unreasonable to hold others to a standard of fairness when it comes to downvoting.  (I believe there's a term/word for holding others to a standard to which one does not, oneself, conform/adhere.  Hypo...something.  Hrm, if I could only remember the rest of it...)

LOL. I'm on that page, too!  No practical use but I want it anyway ... for no good reason at all.  If only the bank account were bottomless...

That's nuts...
 

You're in luck, as you can readily purchase a Chiappa Rhino, which fires from the bottom cylinder like Vash's gun.

Here's a link to a read on it, since you seem interested: https://www.guns.com/news/review/gun-review-chiappa-rhino-revolver-in-357-magnum

If you want to pull your downvotes, I'll be happy to discuss it. It doesn't seem fair to downvote for something when you didn't understand the complaint. 

No, that was the other guy who complained you should use Gm's common sense and not also make rules by Fiat. Which is silly. 
 
 
Agreed.
 
Yes, I would prefer that there were rules to cover it.  Which was why I went with the house rule I mentioned earlier.
 
However, the other guy refused to let it drop and kept exclaiming the the rules as written were 100% fine with no need to make a house rule. 
 
 
 
Which seems totally cool by me. I wanted to start this game in 4th edition, but Hero Designer is just too easy to use and without something comparable for 4th, I couldn't justify the time I'd spend statting out everything on paper. 

That seems unneccesary. 
 
Of course I can use the rule from 6E, but it doesn't fix the problem. It just takes away the benefit of running around someone in a circle, it doesn't actually remove the ability to do it. It doesn't remove the ability to run past combatants and ignore them to get behind something or someone they are defending which are additional concerns about the spinning dance mechanic. 

I'll have to disagree, as I feel several crossed the line. 
 
 
Sadly, the other guy just went through and hit a bunch of posts of mine with Downvotes, even those that had nothing to do with him. So, there's your target audience. 
 

So, in 5th Edition, Defensive Maneuver makes a big deal about attacks 'from behind'. However, other than 'surprise attacks' (which I find vague and unclear other than when the target is completely surprised) I can't find a reference to the benefit of attack from behind or to the side, basically I can't find any facing benefits or penalties.
 
Can someone point me to them please?

That of course isn't, but the discussion wasn't about group table rules. It was always about the GM exercising 'common sense' and making a ruling or restiction, which would by definition be ruling from GM fiat. I understand why the other guy can't admit that because it would mean admitting his arguement was inconsistant. Why do you care about the terminology? How is a GM passing a judgement call/house rule, for whatever reason, not GM fiat? And I get the vibe that if it were, that would somehow be bad? Am I picking you up right? Why would that be the case?
 
 
No, and you've been nothing but polite and helpful. I have no issue with you (or anyone else on the board).
 
What I want is to be able to discuss issues with the system without someone edition warring or making snide insults against me or my group. I don't care if someone disagrees with me,  I just don't like insults and edition wars.
 
 
 
My players just came from playing a very tacticle game where positioning was ultra important, so yeah, they are doing everything they can to get into a better attack position. Despite insults to the contrary, there is nothing inherently munchkin about using the rules as they are written. Most games with map based combat avoid this sort of thing with either an engagement rule, abstracting combat so position doesn't matter,  or, more recently, attacks of opportunity (or the equivalent). But when they aren't there, and facing is an issue, and position matters... it's natural to attempt to maximize bonuses.  I think Hero just needs to pick one or two of those options (or be house ruled as I have done) to fix the inconsistancy. 
 
But yes, it's silly and I've fixed it with aborting to attack someone if they try something like that (this also allows some tacticle exploitation, because if your armored mate runs past and eats their attack, your lightly armored figure can go after without fear because they have already aborted).