Looking for a non-AR shit-hits-the-fan weapon platform

So, I have been looking at a lot of rifles lately. I think I have settled on a platform that is non-AR, but with extremely available 5.56/.223 ammo accessibility. There are literally probably a billion rounds of 5.56 ammo in the U.S. just laying around. So, I have factored in a few conditions on my choice of SHTF primary weapon. I carried an M16/M5 weapon for 24 years in the Army. I am intimately familiar with the weapon platform. However, I have never been a huge fan of the cookie cutter AR platforms.

I was initially looking at Sig Sauer Spear AR-10 7.62/.308 platforms but have recently changed my mind about those.

I have never owned, nor fired a bullpup combat weapon… but I am finding myself attracted to them.

In particular I’ve been watching every YouTube video I can find on the Kel-Tec RDB 5.56.

So, I know there are some fellow military weapon connoisseurs on our site… and I’m asking for your opinions.

Good? Bad? Or ugly?

It accepts all STANAG M16 magazines. It will cycle 5.56 and .223 effortlessly. I can put a standard Red Dot or low power 6x or 8x power scope.

I literally have the gun saved in my cart, waiting for me to pay and be sent to my local FFL Dealer.