TBH, in 100 years I do not think guns in general will be using projectiles. If they are, the weapon will most likely be using magnetism to throw the projectile as opposed to bullets.
Think a mini rail gun.
Laser type weapons will most likely be in use as well.
Unless of course civilization has fallen and everybody is back to sticks and stones.
Just my thoughts.
It’s possible that the propellant could change significantly, especially if a future conflict prompts the military to explore new options. There’s a huge influence of military weaponry and civilian products. Of course, as I’ve joked before, if the Army invented a working lightsaber, the first thing Congress would do in response is ban them on the civilian market.
I’m not sure what firearms will look like in a hundred years, but I know that only our robot overlords will be allowed to have them.
Maybe in 100 years we will be beyond Fighting, Battles, wars, Riots, Gang bangers, The need for Policing…
NAH! WTF was I Smoking ? I’m going to just chill over here and be quiet for about (3) hours… ;c)
Red dots, lasers and lights will adorn handguns of the future. They will be built in and integral to the firearm rather than add-ons gizmos bolted to the gun. For example, Lasermax’s guide rod laser or a light built into the guide rod or an improved version of the flush Meprolight FT Bullseye sights now on Sig P365 SAS.
Electronics will feature rechargeable batteries that get their charge from a charging station, a magnetic charger or some micro-USB rather than today’s practice of going to the store in search of some unfindable battery. Olight’s rechargeable weapons light batteries are leading the way.
Lead projectiles will fall to high-tech copper or other metal or polymer materials. Bullets will rely on profiles like ARX or Lehigh for terminal performance rather than weight and expansion like traditional lead bullets making smaller calibers more effective. Imagine a 22LR with an ARX bullet.
It’s a toss-up whether civilians will be allowed to possess firearms at all 100 years from now as the world races down the slide into socialism. The firearm one actually possesses 100 years from now may be a contraband century-old handgun and 100+ year old ammo.
Well, the 1911 is over 100 years old and it’s still a current design in production. My fear is not what handguns will look like in 100 years, but whether we will have access to them at all…
I think we will have phasers like on Star Trek.
You know Sir I think I am addicted to 1911’s… oh hell, probably lets just say all firearms! who’s kidding who right?
But the 1911’s…even the Tisas or Rock island Arms Rock Island Armory Rock Ultra HC 10mm 5" Barrel 16rd Semi-Auto Pistol –$700 @ Classic Firearms… Oh, they get my Juices Flowin’
Ergonomics dictates design.
1911 is still going strong because it’s tough to improve on Browning’s masterpiece.
I found the article more interesting than I thought I would. I struggle to argue with his point of view, logic, or conclusion with one exception.
The advances in technology seem to be multiplying exponentially. It seems to me (and I could be wrong) that a large part of his assumption is that the progression of the next 100 years will occur at about the same pace as the last 100 years. If he’s assuming that, then I disagree with that assumption.
How will the speed of technological advancement change handguns? We will see and the author may be spot on.
Or the pricing will be so out of reach that only few will be able to afford them. Oh, well, back to the zip gun.
If the current administration continues with the coup…
If we stop the coup…
So if you think my new futuristic gun is improbable, look at your phone…
My Bones will be dust my friend… and I’ve already vowed "I’m NOT coming back here…I think I will try PLUTO next and all I will have to worry about is “Marvin the Martian” and his vaporizer gun !
Not me, I’m coming back to haunt these fools, including their offspring!
For eternity. I hear that’s a long time!
OK, here we go with the scary face S— again guy’s… If I was a vindictive kind of Gunner I would hunt down an even worse picture of o’biden …but since I’m not… Who-wee ! Man, it’s like what Hunter would look like in a couple of years, my eyeballs are bleeding thanks a lot
Would it be a bad thing to have a phaser instead of a bullet? The ability to stop a threat without lethal force sounds a lot better than biting the bullet and having to live with the life being taken.
Then there is the neuralizer?
A way to reinsert a person in a new direction and a better path.
Then there will be the husband who zaps his wife or via versa and has them doing the dishes and enjoying it. 
100 Years passes faster than you think. Quote from a country artists song 
I don’t have more than a few decades left here, but I do hope that in my time we don’t see firearms change too much. I know electronics are being attached to firearms, but for the most part, a gun today works pretty much like it did 100 years ago, and I like that. Electronics have made their way into almost every aspect of life, so its kind of refreshing to have devices that are totally free of batteries and chips. My revolvers work just like they have for a century, and my semiauto can trace its design straight back to Mr. Browning. Other than plastic in the frame, its really unchanged, and its just as effective now as it was then. I like that.