People confuse the sensation of the action cycling with recoil.

I had a 7.62x39 upper that was cartoonishly overgassed. That round doesn't have much recoil, but the buffer jackhammering on the end of the receiver extension left a bruise.

This is correct.  The carbine length gas system was created for 14.5 to insure enough dwell time for reliable operation with the shorter (less than rifle length) barrel.  For 16" barrels the mid-length system is ideal.

Barrell vs Gas System
14.5" - Carbine
16" - Mid
20" - Rifle

Honestly, the AR reached its pinnacle with that combination from PSA. Everything else has been hotdogs in lime jello. Unnecessary and sometimes gross.

Personally, it's a more smoother shooting rifle in mid gas to me.

Honestly, lol no it has not. I own that too and I also have a Sionics mid length that makes what you just said even more unnecessary and grosser. A waste of money on jus as gud really.

@Number1gun  you are missing my point.  Both rifle and carbine length gas systems were designed to provide 7" of dwell time on the barrel lengths they were designed for; 20" or 14" respectively.  Carbine length gas was not designed for a 16" bbl.  The 16" bbl is only a thing as a result of NFA.  

So the civilian market had a choice of 2 gas lengths to use on the 16" bbls they were forced to use because of NFA - rifle, or carbine.  After enough people used carbine length gas system on a 16" bbl and realized the sub optimal performance that combination produced the mid length gas system was introduced to correct the problem.  This is also why true dissipators (rifle gas on 16"bbl) never really took, 3" of dwell time only works if you blow out the gas port to a huge diameter and even then doesn't work great.

It is a misunderstanding to assume the carbine length gas system was meant to go on a 16" bbl - that combination only exists because of laws.  

Does that make more sense?

LOL, K…

Wasn't the carbine gas system originally used with 10" barrels? I think the 14.5" barrel came later in conjunction with it for those reasons, but not the other way around.

11.5 to 12.5 - carbine
13.9, 14.5, to 16 - mid
18 to 20 - rifle

LOL, K indeed...

Whoa! Are you telling him not to like something you don't like?

JK, Sionics is good to go. I have one of their NP3 BCGs that will probably go in a 6940.

Careful… you’ll end up on the ignore list for forcing him to like something.

again, I'm not trying to give a history thesis here dude, I'm just explaining the design intent and the role of 7" of dwell time.  I mean, it sounds like we both agree that's the "Avogardo's number" or whatever I called it originally.  lol, that was my only point man.  That there is a method behind the madness of all the various gas and barrel length combinations, and the issue of dwell time is the common thread that brings some combos to the top over others.

And primarily refuting the dumb fuck comment of that other dude with actual reasons.  But you can take the reins on the history portion man, I'm cool with that.

Are the pig-tail pistol gas tubes finally gone, or is that still a thing?