Legal barrel length is 16 inches.
A 14.5 in barrel with a muzzle device that is pinned and welded into place brings over all length to 16 inches this makes it a 16 inch barrel.
A 14,5 barrel without muzzle device pinned and welded....even though length is 16 inches does not make it a legal barrel.
So the advantage is you have a little shorter barrel while staying legal.
An ar pistol can have any length barrel you want. 7 inch....8..inch...10...11...however an ar pistol must have a pistol brace instead of a traditional stock.
Look at the bcm link I posted before.
As far as pistol vs rifle,,,,,its all about barrel length and velocity. There is a happy medium.
In 556....I think most would agree that the minimum velocity/force barrel length would be 11.5 or greater.
And this varies for different calibers.
Most would agree for a first rifle.... 14.5 pinned and welded is a smart start. Can take out baddies.....and can ethically hunt with.
Can't go wrong with these two
I've bought complete rifles. I have assembled rifles from parts from different manuf. ( I hate the world build.....Cause I ain't building crap....I'm assembling like legos)
Nothing is quite as nice as a complete rifle from one manuf....maybe when time is right change the trigger...
https://danieldefense.com/m4a1.htmlhttp://shop.bravocompanymfg.com/BCM-RECCE-14-MCMR-Carbine-AR15-p/bcm-carbine-780-750.htmAnd I agree with everyone else's responses as well. Everyone is right. Pistols, rifles.....short barrels 14.5. 16 inch ...556...6.8...there is no wrong answer