I understand that, but I would like to understand the mechanical differences that free this musical note from the rifle. I want to understand the how and why of the ping occurring. What mechanical force is making the ping?
You are getting too intelligent for me!

Darned if I know. All I can remember from working around the Uber Tuned M1A and M14 rifles in the NRA High Power circles is that a properly tuned stick or gas gun pings like mad.

I'm trying to keep it simple here.
I will start by either shimming the gas cylinder or fine tuning gas cylinder locks so that the gas cylinder assembly is uber tight. Currently my gas cylinder assembly you see in the video is welded/unitized (read it in the stickies above).
Then I will start selecting gas cylinder locks (I will have up to 6 or 8 of them at any one time) to fit that gas cylinder WITHOUT any shims whatsoever. I try to have the gas cylinder lock 'time' or contact at around 3 or 4 o'clock (clockray method) and then plastic/rubber hammer to 6 o'clock. That is gonna be fricking tight. Needless to say, the entire gas cylinder and barrel will vibrate as ONE unit; think bolt gun precision rifle...
Now the flash suppressor has the machined tines that tend to ring like a tuning fork effect when lightly tapped on a wooden surface (or any hard surface). When your 3 splines on your barrel (go and remove your flash suppressor and have a look) are peened or disrupted, that flash suppressor will need to be installed with a rubber/plastic mallet. No specific tension on the castle nut is required, just snug it up. Avoid over torquing it and you won't bend the castle nut pliers like some doofus over enthusiasts have done.
And finally the third but not always necessary for a hunting rig; glass bedding that rifle into a specifically designed match stock (no CHU wood stocks, please don't get me started). When one purchases a specifically designed NM stock like the Mcmillan M1A stock or their pistol grip designed sniper rifle stocks, it's only fitting that you BED that barreled receiver into that NM stock. They are designed to be the most rigid for precision shooting, something you don't always desire when hunting or the zombie apocalypse. Now, the entire rifle will vibrate as ONE unit; and I miss that 'feel' since my M1A is my teaching rifle and has to be pulled apart very often. Match guns DON'T get disassembed much during the year/shooting season until around December / January buy the person who built your rifle. Am I sounding too serious here? I am doing so deliberately. Some of you have asked me about hunting with such a rifle... it's a very expensive proposition. You are better off buying one of the Canada Ammo shorties..

Hey, maybe I should do that!
Back to the gas cylinder locks... where does one find a pile of Norinco gas cylinder locks? I don't know and don't look at me. I do this specific kind of tuning ONLY to USGI dimensioned barrels (can you say: Criterion, Hart, Obermyer, Smith, Douglas, USGI 12.5 takeoff?) since I can buy a pile of Springfield Armory gas cylinder locks from Brownells quite easily. That's why I do things this way! For the Norc lovers who want to tighten things up on a budget, I make up these shim kits for you. Honestly, one only needs a shim or TWO. The kits I sell for $ 5.00 will easily satisfy 2 or 3 Norc rifles if you get together with other M14 owners. And it's the cheapest to pay me with a $ 5.00 bill by mail.
Anyways, I detest explaining all this with a keyboard because approaches like these tuning methods are best done at a clinic or a video. And right now video options are not available for/to me to reach all of you. So the clinics out west will just have to do. Or in 2 weeks I will be in Fredrickton, NB for a clinic.
There, I hope all this typing explains how and why we tune the front end of your M14 rifle! If you are a moose or deer or bear or elk hunter, then don't bother doing all this stuff! Whoops, I forgot about the zombie apocalypse preparedness dudes!
Cheers all,
Barney