Am I right in thinking that a AR15 with a 14.5 barrel would be better off shooting 69bthp for SHTF MODE? Rather than M193??

I would say yes.

Because 69gr would frag at lower velocities.
Would be more accurate.
Should penetrate autoglass and light armour as well or better.

Downside, much more expensive.

Now the heavywieghts can back me up or shoot me down. [peep]

Yes. Even better would be the Black Hills 68 gr OTM if it shoots as well in your carbine. The 68 gr version has a shorter neck (it doesn't have to travel as far before fragmenting) and performs very well. And should you have a gun with a 1/7 twist barrel, then the Hornady or Black Hills 75 gr OTM would be a better choice than either. All fragment well but some do so sooner and more dramatically than others. Either should be more consistent both in terms of accuracy and wounding potential than M193 and I can say that the Black Hills versions also have little muzzle flash as well. It's only negative is cost, but the Black Hills stuff really isn't all that expensive with all things considered.

-Charging Handle

Coolness Ive reloaded Pistol ammo for years?
Maybe it would be worth while to buy  223Dies and load up some 68/69bthp?

My favorite load.

Hornady 68gr BTHP match RLDR 15 powder.

Book lists ~3000 fps for max load.

Extremely accurate out of my 1/9s. I love this bullet.

Checking on some reloading myself -what powder
weight did you start at-end up at??THX