How much better is the Stoner AR-15 design compared with...

... the M1 Carbine design? Consider also the direct descendant of the MI Carbine floating piston design which is the Ruger Mini-14 in .223 Why has the mini-14 gone out of vogue? Functionally, I'd still prefer the Carbine in its original chambering as a long-term self-protection weapon.

 

Hello,

The M1 Carbine is a continuation of the Garand design, which is just not a great design by modern standards. It was great in WW2 because we were able to make it work, and work pretty darned well. But the offset operating rod design is an opportunity for so much to go wrong both in manufacturing, and it use. Notice no other countries really copied the design while we were foolishly playing around with the M14. For the rest of the world, once they saw the more direct line gas piston design of he SVT40, most went that way, or to a completely different system. The 1941 Johnson was created to address the significant challenges in manufacturing Garands and Carbines, it just came too late. But Melvin Johnson completely removed any gas ports on the barrel, and the reciever was investment cast; which was bleeding edge technology in WW2.

The design challenge for Gene Stoner was to fix all that was wrong with the Garand design. The first of which was doing away with moving parts connected to the barrel, which was detrimental to accuracy and would lead to the need to completely rebuild a rifle at round counts as low as 3,500 rounds.

The M1 Carbine really was one of the most successful small arms programs in US history, and they're wonderful little rifles for sure. But technology moves on...And even the AR15 is getting awfully long in the tooth these days. Look for it to be replaced by a 6.8mm in the next 18-24 months.

 

The AR design is very adaptable and lends itself to morphing into different shapes and types. It's the most "modular" of all the modern battle rifles. The M1 Carbine wasn't nearly as adaptable.
Both shoot cartridges that are low on recoil and very manageable for the recruit. However, neither one would be my first choice to take into battle, but if I had to choose between the two, I'd definitely pick the 5.56! They've been trying to come up with a replacement for for the AR for some time now but nobody has come up with anything that's significantly better. Likewise with the 5.56 round.
There never been one battle rifle that can do all jobs well. That's like trying to play golf with just one club! Our government should augment the AR platform with something that has more "oomph" at long range, teach soldiers how to use both and then issue the rifle that best fits the circumstances.

 

The AR design is brilliant for it's day, and it's still a very relevant weapon. I encourage you to take a look at what the US Army is developing right now. The competition is between (IIRC) General Dynamics, Textron, and SigSauer. All use next generation ammunition that is between 15%-30% lighter in weight than the 5.56 yet has higher performance. It's the ammo that's really driving this...Even a 15% reduction in ammunition is too good to ignore from a logistics standpoint, and 30% would be a near miracle. The ammo is either polymer cased, or case telescoped. Also, another reason for picking a new cartridge is body armor. Cheap plate carriers available on ebay can defeat any and all 5.56 cartridges currently in service with any military. Tests with tungsten bullets have shown an improvement, but they found they really need a bit bigger bullet than .22 to get the performance they want, so that's why all contenders use essentially the same bullet even though the rest of the cartridge is very different from each other.

And while the AR still works just fine, there have been advancements in rifle design that can reduce manufacturing time/costs; so that's why the AR isn't part of this new weapons program. I think the most impressive of the 3 weapons is the offering from Textron, but I have a strong suspicion the Army will take the conservative route and go with the SigSauer...we shall see. They have bumped the final decision to 2022, so we'll have to wait another year, but this time I think they'll actually make a change.

New in 2021: Army to pick replacement for SAW and M4 for soldiers, Marines and special operators (armytimes.com)